I don't think you'd get much for a Performa. The Performa line isn't exactly "classic" in the Mac community, as they represent The Dark Ages. My first Mac was a Performa 6200 and it's considered one of the Worst Macs Ever. :lol:
I doesn't hurt to try, though, if you just want to get rid of it. You never know, someone may need an older Mac to run some System 7 or 8 apps.