I have to agree with April, worried about bugs, and other problems with the peat moss.

Aspen is REALLY cheap from the supermarket. I get 1800cu in for like 2.49 Lasts me about 5 changes, but I have 5 cages, and one of those cages is a 30g aquarium.. the other four are 15qt sterilites. So that'd be enough to completely change out one cage like 25 times.