You could get the 50mm f1.8, 28mm f2.8, and 135mm but those are booring.
Try these three canon FD lenses for not too much:
#1: 50mm f1.4 - an abolute must have. Better than the f1.8, 50mm f1.2*, and 55mm f1.2. *Note the 50mm f1.2 FDn non-L version is pretty poor.
#2: 24mm f2.8 - A little bit wider than 28mm and very sharp.
#3: 70-210mm f4 - More versitile that the 135mm, surprisingly sharp.
I own all these lenses Darin and I agree with this entirely, especially your remarks about the FD 50mm f1.4.
A few years ago, when I was just getting into the Canon FD System, I acquired a 50mm f1.4 and shot this photo of my daughter. I don't recall the camera, nor the f-stop, although I guarantee the shutter speed (flash pic) was 1/60th sec. I don't care if anyone else thinks it's a great photo but for me, it's the best and most precious photo I've ever taken. In my mind there's no finer glass than Canon FD.
In life you only get one great dog, one great car, and one great woman. Pet the dog. Drive the car. Make love to the woman. Don't mix them up.