So I'm thinking that the freewheel is going to need to be replaced on my Miyata (I just had the RD and chain replaced) and I was looking into doing it myself, since it seems straightforward enough. I was just curious if there was much of a difference between freewheels. Can I just buy a reputable brand off amazon or ebay? Is there somewhere else you might recommend?

For the record, I've got a 5-speed freewheel on 27" Araya rims. Can I just stick pretty much any 5 speed freewheel on there?