Just going to point out, while there are some spells cheaper on the AH, there are also some that are drastically overpriced. Scrolls from quests are often a prime example of over-priced scrolls.

And before saying the scroll prices for GEO are appropriate, compare the costs of other high level scrolls from vendors to the cost for GEO spells. Only non-GEO scroll I can think of off-hand that is over 200,000 at a vendor is reraise 3.