I was at an auction the other day and came home with an air powered
staple gun. Not one that shoots those little staples like you desk
stapler, but shoots 2 inch long staples. I see these used on pallets,
and often in construction. Using my small air compressor which is
just a basic tire filler, I shot a staple thru a 2x4 and it came out
the other side. Lots of power there.
The best part, I bought it for 50 cents.

But there were only a few staples in it and now that I used them all
up just playing. Where can I buy staples for these things?

The brand of the stapler is Bostitch.

Mark