1. Bulk order from the internet. Get 6 months worth, even with shipping costs this balances out to less than the pet store charges.
2. After hoppers I go to adult mice, in fact I just generally follow the 10%/15% body mass rule of thumb, so often by the time they are pounding 3 hoppers a feeding I either let them eat the rest of the bag and switch (not at once, but in so many feedings) or just switch.
3. Aspen really isnt a big deal, some people panic about it, others dont, really depends. When I used it I never bothered being worried about them swallowing it, because they didnt, and most pieces they would have would have been smaller than the bones in the rodent, and thus would most likely pass fairly easily. But I never had a problem, so I guess that could just be me.

Good luck.