$1500 got me a DIY melamine rack that holds a total of 15 28qt sterilite tubs(3 tubs wide x 5 tubs high) with 4" belly heat controlled by a herpstat thermostat. As far as snakes I got 11 2010s, one 2009 and one 2004(you can see what they are in my signature) If you want a video description you can check out my youtube channel which is also in my signature.
Also another $200-$300 is going to convert my current rack system into two racks that hold a total of 22 28qt sterilites(2 racks of a single row of 11 tubs high). Plus 2 racks to breed rats in because I've found that it could be cheaper in the long run than buying frozen(and cuz I want to try it.lol), thats another $200-$300 to build the racks and fill them with rats +monthly maintenance costs of around $40-$60. Plus another $??? because once you start buying them its really hard to stop..
Then around 2-3 years down the line once you start breeding you're going to need an incubator, and for more than 4 clutches an incubator can cost up to $200 depending on how you do it. And then you have to think about hatchling caging, because your snakes may sell, but they wont sell right out of the egg, and some might not sell at all. The hatchling rack I plan to build is again a DIY melamine rack that will hold 34 shoebox tubs that is gonna cost around $150-$200. So theres an addition to the investment you have to put in.
So like I said before, you NEED money to get going big in this hobby. And you NEED to be able to let that money sit for 2-3 years before you see any returns.
Oh, and you also have to be ready for the (non financial)stresses that come with keeping BPs. Things like them getting sick, them going off feed(I've had one off feed for nearly 3 months now), them laying HUGE dumps in their tubs that you have to clean up...etc