When I first started out with Ts, I always used crickets, and then I went to roaches for awhile. I got lobster roaches(forgot sceintific name), and they weren't the best for my inverts; didn't grow as big as I thought, climbed, burrowed, and some Ts just didn't like em. Now for the past few months I've been back on crickets, which is fine, but I'm thinking about getting some of the species you got, B.lateralis, because I heard they were really good feeder roaches.do you use crickets now? I just got some Blatta lateralis, and my Ts love them.
Ordering over the internet is probably the cheapest you can get, next to breeding them yourself.
Better would be starting a roach colony, more expensive at first, but ultimately free.