>>1992551ok sorry. So I guess 250 would only be (somewhat) worthy if you really like your bike and you pretend a good wheel and an excellent thread repair from your bike shop.
If not, better buy another second hand bike and try to sell this one.
If you do it by yourself, Changing the wheel would mean at least having the tools to unmount and mount the cassette (chain whip and tool). So starting from zero let's say 100? bucks for the cheapest built wheel and tools. then 10 for brake pads.
Are you sure your derailleur is welded and not replaceable like picrel? If not you would need a T-nut (5 bucks) and a drill, or a tap AND a coil. (maybe 20?) If i'ts repleaceable you could get a new derailleur hanger for 10.
