I found my heating pad on ebay for $12 shipped, great deal and its almost impossible to find them w/o a auto-shut off in the store. With the low amount of roaches your starting with, keep em all in 1 bin. If i were you, id try to bump up the numbers your getting. More you get, faster you'll be able to start feeding from the colony. With those low numbers, i would say 4-6 months before you start dishing out of it. Try to add some more adult trios (2 girls, 1 boy). The Roach Ranch & The Roach Guy both sell trios for $1.50 or so, and thats dirt cheap for what your getting. Get another 15 girls to speed things up, the last thing you wanna do is start feeding early and wipe out your colony and wait again a few months.