That's my suggestion. eBay is drowning in freewheels. I've got an extra one lying around somewheres and another on a wheelset I don't plan on reusing.

Then there are the new ones available in lots of places.

Cranky, given what you've been riding on and your favorite ratio is either 52-19 or 42-19; if you decide to go with the compact, get a 50-36 with a Shimano 5 speed freewheel 14-17-20-24-28 for $20