loaded question but 05 runners are advertised for 4500 up to near 6000,it all depends on mileage,has it sat outside in the rain and turned to salt
if its just a belt or even altenator trouble it would not be that expensive to fix
whats it worth 3000+
Not much. Scrap value if its not running. Fix it first to get a market price, or if you can find a mechanic who is confident in his diagnosis of the problem you may get a few bob more. It may be a great bike behind the squeal, but a crap bike running without sound effects will still fetch more.