Hi. The suggestions given above are pretty good. The only thing I would think may be unnecessary is the radiant heat panel. If you keep your temps in your home at around 70 you really shouldn't need the radiant heat panel. I have 13 bp's and all they have is belly heat...the ambient temp is in the 80s for their containers (i keep mine in tubs). If you use a aquarium then you can modify the lid and add a heat lamp to the setup (I have this setup for one of mine). I got started with my first ball for pretty cheap. Check your local pet stores they sometimes have full setups with a majority of what you need and they sometimes go on sale also.
I got a Zilla 20 gallon setup for $170 that included light dome, analog thermometer\hygrometer, reptile carpet (i dislike lol), uth, screened lid, water dish
so that leaves:
Thermostat- ~$50
Screen Cover Modification- ~things around the house
Screen locks- ~$4
Heat bulb\Ceramic heater- ~$10 - $20
Hide- ~$0 - $10 (many choices from bowls around the house or fancy pet store hides)
Temp Gun- ~$10
So total around $260 for this setup.
My personal setup now (minus the rack i am building)
For one snake baby to juvenile:
sterilite latch 15qt : $4
Cut Plastic Bowl for hide: 3\$1
Water Bowl (small heavy croc flat bottom): $1
Kraft paper(substrate): 12in X 640ft $14
1ft section of heat tape: $2.10 (if you want pre wired $7 reptile basics)
Thermostat- ~$30 (hydrofarm)
Temp Gun- ~10
Total: $67!!
btw I am working on a different stat for my rack (stc-1000) that is only 13.99 shipped on ebay but you have to wire it yourself (lol that was fun to figure out but i am going to power it up tonight!) so take a look at my thread later on if interested when I update.
Oops sorry for the handling I really only handle my Normal as he is my first BP and by far the most chill. All other snakes are handled every couple of days to inspect for overall health. Mystery is the most fun of all lol serious defensive striker!