Aspen is aspen is aspen is aspen, as long as it is only aspen and not mixed with anything or chemicals added for whatever reason.
Personally I like the shredded stuff, which if I recall is usually how the reptile stuff is sold...and the rodent aspen is usually the shaved stuff. I like the shredded stuff because it seems to hold up more to tunneling. I have been lucky and found an equine/farm store that sells aspen bedding for horses and it is more similar to the shredded aspen. I get 45 pounds of the stuff for about 5 bucks. I've had it for a few months now and have barely put a dent in it after multiple cage cleanings.
Here is a pic of what I get, with a 6 qt sterilite for comparison. So yeah, might be worth trying to find a farm supply store to see if you can find anything, because this is a good deal! It is a local product, but there might be something similar in your area.