Cheapest way I did it when I started was to check local Craigslist. I found a guy about 15 mins from me who had 2 colonies going and had tons of xtra females. He sold me 50 freshly molted females for $0.80 each. Best part was I didn't have any deaths like you always get from shipping. Of course those 50 females was to bolster the already 80 females I had but that batch had a rough start. Seemed shipping didn't go well for that batch and 1/4 died for some odd reason. Now though 4 months later and I got babies coming out everywhere and Harley has decided her new favorite food now is butterworms :roll:
As for kits, you can buy all different kinds and sizes and stuff but imho don't overthink it. I did and spent time worrying if the temps were right, this was right, that was right. In the end I just used a 45 gallon Rubbermaid Roughneck tote vs a Sterilite tote since the Rubbermaid is thinner on the bottom and thus easier to heat, a strip of packing tape around the top since the little ones can climb the side of the roughneck totes, a Zoo Med UTH, a lamp dimmer from Home Depot for the UTH, and egg cartons from the local feed store which I stack horizontal. All together it was like $40 and the roaches are happy and breeding like crazy. Roaches are roaches and will breed and multiply through pretty much anything.