Confirmed from a few legitimate sources, we can now confirm the shutdown stems from AT&Ts side. The masses of unlockers (mostly the larger guys pushing volume at the under $1 range) used a handful of direct sources to AT&T to fulfill their customers unlocking request (or had direct access themselves). AT&T unlocking requirements were simply not checked as hard or prevented through this direct channel compared to individual contract customers requirements. AT&T simply decided to become more strict overnight and instead of policing the IMEI unlock submissions they disabled a majority of the direct sources access and only left a few options and vendors access intact. This doesnt mean everyone who was working direct was abusing the system. It simply means that direct supply is now limited to far fewer direct vendors. With these vendors having less competition to worry about, prices will go up.
Most unlock vendors have since reinstated IMEI unlocking services on their website along with IMEI Status checks; at a varying cost of $20-$35 per unlock. Expect the cost to remain in the same ball park for the long haul and kiss the days of cheap (under $1) unlocks goodbye forever!