3.4 is a good start! You'll probably want to expand after you get some of those litters raised up and fed off, it is just so convenient. I think that getting our breeding colony up to the point that I could feed everyone and have surplus was one of the best decisions I made. Our feeding bill went from $200-250/month down to about $70-80/month. I also sell my surplus to the pet store or other snake owners and falconers so that helps cover the cost of food/bedding too. I jumped in feet first with good sized rodent colonies (about 15.65 rats, and 40.200 mice), and have had to expand the rats a little since then to feed babies. I LOVE having any size food available at any time, it has made keeping a continually growing snake collection that much more enjoyable.
I guess what I'm saying is, I recommend getting a good sized colony going, you won't regret it. Hopefully these first few litters will also help you see the light. Good luck with those guys!!
-Evan