GF3 Ti200 goes for $150 new and many can overclock to faster than your GF3. New GF3's still go for $200-340 but only suckers are buying now since the GF4 ti4200 will be out for $200 in 2 months.
I'd say $150 is a decent price, especially for a friend -- online you might get $175-200. eBay you might get $250 since some buyers there are idiots