Craiglist or cbrforum.com or cbrworld.com will be your best bet for an F3.

Due to the age of the F3 (last sold in '98 I think), you'll probably have an easier time finding SV650s.

Good luck finding a stock F3, most of the few I have seen had been converted to track beasts

I'd shoot for a Katana 600 instead... TONS of those around and they'll be as cheap or cheaper than an F3