I found some 1.5# hand weights at Walmart (maybe the same ones Erica has?) but I hated them! The weight in them was stiff, and they were uncomfortable. I got rid of them quickly and stick with my 1# Ironwear gloves (VERY comfortable).
2# is quite a leap, and could stress the elbows and shoulders too much, IMO. But you could do maybe a small portion of a workout with 2# (slower punching segments?), then switch to 1# for the rest. Or make those 1# work by punching more powerfully (emphasizing the retraction of the punch to avoid locking the elbows).