I'm involved in an interesting project to fix up a 1950 MG TD as a "hot rod." I bought this very rusty car for transmission parts last summer. We think it is a low-mileage car that got caught in a flood. The internal tranny parts were like new. But the chassis and body are very rusty.
I am currently working on the front end parts: brake drums, A-arms, coil spring pans, coil springs, etc. After spending the better part of an hour media blasting one A-arm in my Eastwood (www.eastwood.com) cabinet blaster, I looked this part up in the Moss Motors (www.mossmotors.com) catalog and found I can buy a reproduction for $14.95. For an additional $5.95 I can buy the lower A-arm pivot pin that is rusted so badly onto one of the A-Arms that it's like it is welded there. So, for about $36 or so, I can purchase two new A-Arms and a brand new lower pivot pin.
If my time is worh just $40 an hour (cheap for restoration work these days) I figured out that I can spend $36 to get new parts and save the three hours of work ($60) I'd have to invest in blasting rust and pressing out the stuck pin. So, it makes sense to buy the reproduction parts and I'll bet I can even sell the old stuff for a few bucks.
After I realized this, I spread the rest of the parts out on a big piece of cardboard and put the part numbers and catalog prices next to each one. Guess what, there are 4-5 parts on each side of the front end that I can replace with new and come out ahead "dollars and sense wise." Not every part is reproduced and not every reproduction is cheap enough to make the math work. But when it does work, why not get the new parts and save money in the process?