The
Roach Barn sells colonies of 20 females, 8 males, and a mix of a hundred or so mixed sizes for 25 dollars. I bought this once already (will buy again soon) and I can vouch that I received it in very good condition. She didn't cheapen out on the packaging, she used a plastic bin and everything. I also saw that shipping cost 13 dollars when she only charges 6. I really really recommend.
I have also gotten my first females off of ebay! Their prices keep going up, but
here's the listing I've been using. Current price is 10 females for 19 bucks flat shipping and all. When I ordered, there were no DOAs.