Where to get them... hmmmm good question. I got my starter colonies from friends but I'd bet that you can find feeders like these at herp shows. The person who got me started on the lobster roaches I believe did get hers at a herp show in the first place.
As for mail order, I had a problem with my hissers once, I wrote to this guy at:
http://www.snuggeybug.com/index.html
He was very helpful even though I bought nothing from him.
Since he'd help a person who's not even buying anything from him, he's probably a good person to buy things from.
My problem with them was that they had mites. It's normal for them to carry a few mites that are exclusive to them without harm to them or any other species... but my problem was that the mites had gone overboard and were causing problems. I tried predator mites but that didn't work. The man from Snuggeybug suggested shaking them up in a bag full of regular old cooking flour to knock the mites off of them, so I did it & it worked! lol
I'm sure if you did a Google search on Caribbean lobster roaches, you'd find someone who sells them.
My box turtles are ornates which means they are a little more carnivorous than the other box species so my boxies, my aquatics, & my frog really like these roaches for food.
I like breeding them because then I know what food is in the bugs before my herps eat them.
Good luck on your search for feeder bugs. 
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PHRatz