This is what I am doing, and this is just me. No hard fast rules here. I have a few normals, and I decided I want to start breeding. I built a rack to hold a lot of snakes. I felt it better to do that than need more rack later on. I bought a pair of real nice mojaves to start with. I got them young enough that it will give me time to get an incubator.

My rack has enough room to expand to a few more breeders later on, and a place to house hatchlings/yearlings until I sell them. As big as it is it will only hold 18 adults and 18 sets of babies, and I have a lot of space taken up by this.

Most of my money went to a rack, heating element, tubs, thermostat (you need it so get a good one), temp gun, thermometer, hygrometer, water dishes, hides, substrate (gets changed a lot), cleaning solutions (used at least 3 times a week), provent-a-mite (you need it so get it before you get mites), feeding tongs, feeders (buy in bulk now, it is cheaper), and a few books.

Most of it all was cheap, but having to re-buy most everything ten times (once for each snake) gets pricey fast. Not to mention having a little extra set aside for vet bills just in case.

I use paper towels for substrate, it is easy to clean and will show you if you have any mites or not. I clean individual cages probably three times a week because of the snakes pooping or peeing, or spilling water out of their bowls. Each time I throughly clean the cage and replace the paper towels. I use latex gloves when I do this too so you can see the expense of the paper towels and gloves and cleaning solution.

I will not start getting a return on any of this investment for at least two years, then it is going to be a guessing game on what I get. I will hopefully have normals next year, but that is a small drop in the bucket to what I am spending. I am not doing this to make money, but because I like it. If I were going to make this into a lucrative business then I would get a business loan and buy into a breeding business that will start producing some good morphs for me now.

This is just my opinion of course. YMMV