Step 3: Motors
As they're common enough you can salvage them from old cell phones and pagers. The only downside is that they can have a large range of power, and some might not be strong enough to meet your needs.
If you need to buy them look online. I sell them on my website, and so do such sites like All-Electronics and Electronic Goldmine. They can be found for between $1-2. No matter where you get them, just don't get them at Radio Shack. They're a total rip-off.
In the picture you'll see lots of types of motors. There are countless types, but these are some common ones I've picked up for salvaged.
When buying here is what you must keep in mind:
1) Does it have soldering tabs?
You want a motor with tabs, not wire wires. If you get one with wires you'll have no place to solder to.
2) Does it meet my power needs?
You need one that is rated to work at a very low voltage, 1.5V should be your aim. Most will do this just fine but I've occasionally run into some that need 2.5V or even 3V.
3) Is it strong enough?
You can buy some really small vibrating motors, but they're not going to be strong enough move your roach. Ones that are usually 15mm - 20mm long seem to do the trick.
4) Did I just buy a pancake style vibrating motor?
Goodness I hope not. While they work great for certain things, they don't work well for this project.
5) Did I pay too much?
If you're paying more than $3 for a motor you're paying too much, especially when you figure in that shipping is never free. Just buy one off one of the websites above when you're buying some other hobby items. Find a couple of little projects on instructables and make an order. It saves on shipping.