Knowing what Mark has repaired - and what other BF members have had repaired - I am really looking forward to the pics with a sort of morbid curiosity! OP, hopefully you didn't suffer as badly as the bike did in the car-to-bike contact.

I think given your budget you can easily find something of high-quality worthy of wearing the parts from your current machine. Assuming you find a frame with the same tube diameter and rear spacing, the only parts you may have to swap would be bottom bracket if you go with something Italian and headset. Headsets are always tricky, because if one is installed correctly the fork steerer is cut precisely to match it. If the fork on the new frame has a steerer just a little too long, you'd have to cut it to get a good installation. If it were just a tad too short, too few threads would engage and could affect the integrity of the interface. In simple terms, stack height of your current headset must match the new frame's fork or you're going shopping for a compatible one.

Check current Ebay sold prices for the same BB with Italian thread just to know ballpark what you may be paying for one of those. Assume for now your headset will transfer over. I'm thinking that's leaving you with 500CAD to put on a frame. You will find lots of nice road frames (you're still looking for vintage-ish, not modern, correct?) out there for that kind of money.

DD