Bicycle Mechanics - New derailer advice

I need a new derailer after a crash which bent the fram and the derailer into the spokes. A guy at my shop managed to bend the frame back into almost perfect shape but the derailer is out of line and I'm experiencing more problems shifting.

My bike is an '86 Bianchi campione d'italia. Since it's a vintage bike I'm not sure just any derailer will fit, nor do I know much about them in the market... how much you have to spend for quality, etc., so can anyone offer some advice? It's a 7 speed cassette.

thanks

btw, also in the market for pedals and shoes. What are some good economy choices for wide feet?

Is it a steel frame? Did the shop guy use a hanger-alignment gauge? First I'd want to know whether the hanger was bent.

Rear derailleur should not be a problem. If you already had a 7 speed cassette just get a 7 speed compatible derailleur (I still can't get used to 80's bikes being called vintage).

As stated above, need to know if a hanger alignment guage/tool was used on the bike. 7+ speeds on the back make eyeball alignment not good enough any more. if it's aligned properly you need a new derailleur - next to impossible to get back proper after a derailleur is tweaked, and the possible repercussions of one bad shift are expensive.

Yes he used a guage. The hanger's almost perfectly back in place. It's just the derailer is a little twisted and so the gears will jump around a little. I looked on amazon and there are a lot of ~10$ shimano parts but that seems too cheap to be quality.