Buying a hood for FD 28mm F/2.0?
I'm sure there are a lot of them around but it's a matter of connecting with the owners!
The original is a Canon BW-55B, which is fairly shallow, and even then there often was some vignetting. You can use a generic one as long as it is 55mm and not too deep. A local camera store is your best bet, as shipping from a store is going to cost many times the hood!