Hub Troub :)
 

I am bidding on a nice pair of used rims on eBay. There is only one problem though...I just realized that the rear hub is for an 8-10 speed, and the bike I was going to put them on is a 12 speed :cry:. Where is the best place to buy new cassettes? Which one would be good to get and is under $30? Thank you! :D

Are you sure that a 8-10 speed hub spacing will fit in your frame?

You need to get the right cassette to match the hub you're buying, you can get that info from the hub manufacturer.

So put on an 8 speed cassette and chain and enjoy the extra gears. That's what I did. You'll have to spread the rear dropouts a tiny bit (4 mm) when you install the wheel. If the cassette body is Shimano, you can buy a 105 cassette for pretty cheap. If it's Campy, Veloce is fairly cheap too. If you're going for "period correct" restoration, then ignore that advice.

The hubs on both my rims and the ones I am bidding on are Shimano, my centurion's components are Shimano. So basically, what it means by "fits 10 speed cassette" is that it can have 10 sprockets in the rear? Because my bike currently has 6 sprockets in the rear.

If you go with a 10 speed cassette, you're gonna have to change everything - chain, FD, RD, etc. And your 6 speed freewheel will not go on a 10 speed hub.

You may be bidding on a "10-speed only" hub. Shimano made them for only a couple of years, and only for specific DA or Ultegra cassettes, so no cheapies.