They don't handle the stress of capture and transport very well. I wouldnt consider a specimen that hasn't been held by a fish store for at least a month. During that time, I would want to see a good feeding response from it several times on something that is easy to feed, and preferably, something I am already feeding my tank.
Mine was incredibly fussy when I first had it. It took over a month for a strong feeding response from it, and that was after it was eating very well at the LFS. The 20 minute drive from the LFS to my house was enough stress to cause it to stop eating. After about 6 months, it would eat pretty much anything that I fed the tank. Ultimately, I had the fish for about two years, I lost it back in November, to what I believe were water condition issues.
I have thought about trying another one, but the thought of finding another hardy specimen is troubling, some estimates say that only 5% of the Potters Angels harvested for the trade are alive a month after capture. It really is a fish that is probably better off left in the ocean, which is a shame, its one of the fish that got me back into fish keeping after college, and Saltwater specifically