Is there somewhere where I can purchase wheels like this for cheap?

http://www.motoreyes.biz/photos/pipe%20track%20wheels.jpg
I need some kind of wheel that has that type of groove. It can be any material. Where could I purchase something like this for less than the hundreds of dollars that Professional dolly wheels go for?

Comments

[onrust]

A chain link fence generally rolls on a pole with wheels like theses.

[Jack A Lopez]

Would skate bearings work?  I am of course referring to the ubiquitous 608z used in skateboards, inline skates, and other things. 
http://www.vxb.com/page/bearings/PROD/sk8zz

These bearings are both strong and cheap, circa 0.50 USD per bearing at the time of this writing.  Also the hole in the center of this bearing perfectly fits a 5/16-inch diameter bolt, so you can bolt them onto things.

These bearings get used a lot in homemade CNC machines, and those 'ibles are probably the best place to see some pictures of these bearings in action.
http://www.instructables.com/pages/search/search.jsp?q=skate+bearing+cnc

[Quercus austrina]

Not pulleys. These the rollers for an overhead or hanging dolly system meant to take heavy loads and move smoothly. Pulleys (from the local hardware store) aren't meant to take such loads and won't stay on a track that can support such loads. Check here, at Servicecaster .

Qa

[seandogue]

Exactly.

And once I thought about it for a sec, I remembered that my parent's home, a turn of the century mansion-ette they bought for a song and saved from the white flight in our area during the late 1960s, has a carriage house (the pre automobile, "proto-suburban" garage) which uses similar hanging rollers for both the main door and an interior door that services what was once a one horse, two pony stable.

[seandogue]

Those look like track wheels that used to be used for over-hanging material transport track before they began using captive setups. I used to know someone who purchased an old factory and we removed the track setup. Really nice, but I'm sure it doesn't meet up with today's safety standards in the US

Still  used for sliding doors. The best I could find with a quick search was a ?nylon? roller version via this link @$91 for a four wheel unit.

[seandogue]

found another for fencing that looks to be more in line with what appears to be a heavy transport roller set, although not a cupped roller
http://discountfence.org/fencestore/chain-link-products/chain-link-fittings/gate-rollers/overhead-track-rollers.html

[kelseymh]

Aren't those just pulleys? Have you looked at your local hardware store? You could also look at your choices from McMaster-Carr.

[steveastrouk]

Yep, they look like pulleys to me too. Should be very cheap.

Steve

[Burf]

I can't say with 100% certainty, but I'm pretty sure those are the top roller wheels for a library ladder or device of that ilk.
You might want to try a search for those or something similar.

[rickharris]

3 circles of plywood with the middle ones a little smaller.