I think you'd be leading yourself into frustration with an ED80 on an EQ3. The ED80 is a great scope but I think you'd get far more out of putting more of your budget into the mount than the optics.
If that's your budget area and want new, I'd probably go for an EQ5-Pro with goto ($999 at Bintel) and put your name on the list for an AT72ED refractor (US$399). That leaves you a bit for a flattener/reducer and other bits'n'pieces.
Alternatively, join the IceInSpace forum and watch the classifieds there. You should be able to pick up a used ED80 and a heavier mount still, for about the same $$.
Steve.