Can some one recommend a good manual air pump for a forge? I'm setting this up for my son and need advice.

Lot's of old ones out there, Buffalo & Canedy-Otto.
Can't tell you a new maker?  Some use a hair drier.

Champion Blower And Forge No. 400 is widely regarded as the single greatest hand-crank blower ever made.

That being said, there are some REALLY awesome old Soviet ones on eBay for reasonable prices. Some of them can be run with both electricity AND hand crank, how awesome is THAT?!?