Auctioneer and subsequent add-ons will scan the AH and purchase everything automatically set at a certain threshold.
Then you just repost everything, and a single checkbox makes sure you are the lowest price within reason.
If you post something at 2c... he will buy it mark it up to 95% of the lowest true value. If he has been on as much as you say, his add-ons have a very firm grasp of the value of every item on the market.
I posted 1500 cloth on the AH... got people undercutting me.. so I bought it and reposted it at my price. Or, I buy it on an alt, and post it higher than my price, and I look like a good deal.