Lamps at Petco/smart run around $15-20 for domes and $35 for a hood type fixture. Don't waste money on a UVB light as they don't need it.
Under tank heater $20 -$40 depending on size. $20 for a two outlet rheostat to control heat. Two dual temp/hygrometers will be $20.
$7 for substrate if you want to use eco earth or the like. You'll need two hides as well which you can make very easily from plastic planter dishes or the like.
Exo terra hide will be around $20. Water dish - again you can do this quite cheaply or a pet store dish for terrariums will be around $20.
If this is going to be an animal you want to display you may want to go with a small boa, something like a Hog Island Boa, as they are more comfortable out in the open.
A BP that is happy will be hiding much of the day, as they are nocturnal and shy animals. Boas can also be much less picky about feeding.