do they make replacement panels for 90 accord rear quarters or would a body shop have to make it

 

Go to majestic honda.com and look up your model/submodel. Probably discontinued but someone may have it in stock in a warehouse. Usually with crash damage a panel is pulled from a parts car. 1/4 panels are a lot cheaper to purchase if you just have to sawzall it off a donor.

You may be able to find a aftermarket supplier for the 1/4 but the stamping may not be as crisp as you would like.

 

If you're going to do the work yourself, you could get flat stock and make patch panels and use plastic filler.