This is a link to a pdf, of how to refill almost any kind of laser printer cartridge. It seems that Samsung has taken to soldering their ID chips to a secondary board to make it harder.
This is quite a list of instructions, while I have never bought from this company the information they provide seems to be accurate (about 180 pages long). My advice is that you look at this document before you buy any specific version (or search the net).
The most important thing about buying a laser printer (or any printer) is cost of ownership / cost of the ink. As most people know printer companies are in the business of selling ink they are almost giving the printer away. When they are on sale it is sometimes at a loss.
For that reason the printer you buy will always come with a "starter" cartridge, this has been going on for many years now. At first they were half cartridges, my latest purchase (all in one laser, scanner printer fax, my old flatbed scanner could not be used by my wife or kids) the cartridge was good for 200 pages, about 15% of a full one.
On my new Brother DCP7065 you can buy the "full" cartridge for $40 making it about 2.7 cents a page, not bad but that is now why I am here.
My color laser Samsung CLP315 (3+ years old) the a set of color and black cartridges is $192 (more than I paid for the printer) no way would I pay that much.
So why did I buy them, the refill procedure is easy and cheap.
Step 1: The Internet Is a Wonderful Thing!
So you see a printer that has all the features you like, DON'T BUY IT UNTIL YOU DO THE FOLLOWING.
1. Find out if you can refill the cartridge that comes with it.
2. How complicated is the procedure and are you willing to do it.
3. Does it take special tools.
4. What consumables do you need.
One is a no brainier, if you cannot refill it what good is it.
Two on the other hand comes in many flavors and depends on how handy you are.
Let's discuss the types of safe guards printer manufactures go through to keep you from refilling your cartridge.
Step 2: Electrical Printer Countermeasures.
This could have been easily been named Printer Counter Measures. Many printer manufacturers place chips on their cartridges. Or in the case of "starter" cartridge have none at all and the printer determines it is out at a predetermined number of copies. Don't try to swap cartridges either the printer remembers it had a starter cartridge and will say it is empty when full.
The "chips" (see picture) have unique IDs and have flash memory that keep track of how many copies have been made. When they reach their limit they "blow a fuse" in the chip that cannot be reset, no more printing ever. I have taken an I2C reader and dumped the contents of these chips and yes you could reprogram them before the expiration but that takes hardware and knowledge most people don't have (I do but I choose to buy new chips I didn't have the time to waste hacking their format).
So what is one to do?
Given you have not bought the printer yet, find out who sells these chips there are 100s of websites that do.
My refills cost about $7 for the chip plus $7 for ink so I can refill my cartridge for about $15 or about 1 cent per page black, color less than 5 cents a page (given even distribution of colors). Compare the color to about 15 cents a page without refilling and you can see where I am coming from. Those pretty reports can with 10 revisions can kill your cartridge quickly.
For the CLP 315 it is a 4 conductor I2C chip pictured here, simply place it over the existing one in the case of the starter cartridge, there is a place it "should" be, orientation matters.
Replacement of the toner requires you get into the cartridge, most have some sort of plug sometimes behind a panel (as it is in my case), research the procedure for the one you want. I have provided pictures of what mine needs.
Shop the web for you chips, you don't have to buy it with the toner sometimes it is cheaper to buy them at different sites.
THINK AHEAD, when your cartridge is less than half full (most newer printers have online counters) or at least when the low light is blinking buy toner and chips. You don't want your kids screaming about not being able to print their reports trust me on this one.
Avoid printers where you must either drill or burn your way through the housing, shoot for the ones with a plug.
The second type of print counter or countermeasure if you prefer is mechanical.
Step 3: Mechanical Countermeasures
Wheels keep on rolling.
My newly purchased Brother DCP7065 all in one has this type of print counter. In the starter cartridge the counter gear is missing. Therefore the printer simply counts up to 200 then quits. If it were a "full" cartridge the gear would be in place as it rotates it eventually throws a switch to indicate it is out of ink.
The first image is of a starter cartridge, the second is of the new gear placement, the third is the kit necessary.
This kit with toner is about $10 so it is cheaper than the chip version.
If the printer you are looking at (many of the monochrome are like this) is like this you may have to purchase a gear the first time you want to refill.
Research how hard it is to do before you buy, in most cases it is just a couple of screws and alignment of the new gear and maybe a spring.
In this case we have a plug and refill of toner is easy.
The beauty of this type is that it can be reset (no chips to buy).
Step 4: I Can See You!
The oldest type of toner replacement counter (not even a counter) is the optical type.
In older monochrome printers they would have a light on one shine through and when the other sensor saw it you were declared low and in N prints your were done.
This is the easiest and therefore not very popular with printer manufacturers. My daughters printer at college Brother 2030 I think had this. She called from school and said it wouldn't print anymore. Given I wasn't up for a trip to her college or to have her buy a new cartridge. By the way if your kid is going off to college (especially if they are in engineering or hard sciences), buy them a cheap laser that can be refilled, it will save them tons of time late at night. The last thing I wanted to worry about was my daughter going across campus to get a copy of a report late at night, small money for my sleep.
Enough about my personal life what do you do?
It is simple block the sensor hole, simply put tape on one end it should be obvious on the cartridge.
As a side note that cartridge lasted 12 extra weeks of heavy use, shows you how much more toner there is left when they say it is out.
Step 5: Conclusion
Having seen the countermeasures you can evaluate printers for cost of ownership prior to purchase.
If you like your printer, as I do my CLP315 keep an eye out for people who don't know about the refill. Mine developed a scratch on the drum and I found a guy dumping one for $20 because he didn't want to pay for refills. Turns out that one had WIFI and I use my olde cartridges in it and even have spares to fill when I get low.
As for the brother we are still in the infancy stage and the jury is out.
Research costs before you buy.
Evaluate the procedure, to see if you can do it.
Avoid the drill / burn type.
Stock up on refills (chips) before you need them.
Refill Refill and Refill, stick it to the MAN!
Remember to remove the old toner!