I just looked on Amazon and the first 3 pages showed 3 different buffers, 2 less than $100, and 1 $220.
There is a difference of opinion on what makes a good buffer setup. Seems most folks want a 1 hp, rpm depending. I've got a 1hp, 3450 rpm buffer and it will move some metal...... AND it will grab a blade and sling it if I'm not really careful. Some folks say a buffer is the most dangerous equip in shop. I also have a 1/4 hp, 1725 rpm buffer that I really prefer.
For a really good mirror finish most folks agree it needs to be sanded to at least 1,000 grit, and even better if took higher. I take to 1200 grit, there it doesn't take much power at all for the buffer - just light touch is all that's required. AND - 1/4 hp, 1725 rpm with 8" wheel is too weak to really grab blades and seems to be much safer to me.
I'm sure there will be others chime with their preference, and many of them (like Ed and others) have MUCH more experience and knowledge than I have in knife making, so listen to them also. As I said, I've got both buffers sitting there, but I just prefer the low power, lower RPM setup. Might be a bit slower to finish a blade.
Ken H>