Standby, because I'm going to sound like one of those infernal infomercials on TV...
I'm a level 34 WoW noob who's been playing for all of a month. I've gone from 7g to over 100g in the span of a week once I figured out how to use BTM. 75% of my take was generated from Auctioneer/BTM and that's using the out-of-the-box base rules. All of this was done by starting small and focusing only on a few low-risk (low deposit) goods, most of which are consummables for the various WoW professions.
It amazes me that players post auctions with buyout pricing less than the sell-to-vendor price! Guess they have no idea that their asking/buyout price is less than what a vendor would offer. I can't tell you how much coin I've made purchasing these, whipping over to the vendor, and dumping the stuff. It's no-risk, guaranteed coinage.
A big thumbs up to the dev(s) and anyone else who helped shape this addon. So if you decide to make an infomercial, can I be the host?