Those Petsmart Rheotstats are okay, but don't use any Thermostat under $50. I've heard many horror stories about them malfunctioning and reptiles being cooked. I'd much rather invest in a $70 Johnson Control thermostat (or better yet a Helix) to save my $170 dollar snake rather than fry it on a $25 electronic. What you definitely want to get that is very cheap though is an indoor/outdoor thermometer so you can keep track of the temps at both sides. Especially with a BRB where you don't want super hot temps, a thermometer is cheap yet indispensable.
A 10 gallon will be okay for a bit, the UTH is good in my opinion because you want belly heat. The best substrate in my opinion is paper towels. It doesn't look that nice but it's so easy to clean, especially since mold can accumulate so rapidly in a tank that must be kept at 80% humidity or higher (I only have one BRB and I still use this to save time and keep the tank super clean). You do want to cover off most of it though, I use Reflectix insulation after hearing about it from Dave on this forum, it's worked wonders for me for keeping in heat with the glass and humidity (covered the screen top with it) for my BRB in the winter.
That's just my 2 cents from being a BRB beginner last year. Congrats on your new BRB, they really are great snakes to look at as well at to handle (mine is at least!). Post pics once you get him/her!
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Danne
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1.0 BRB "Monroe"
1.0 Pastel BP "Sebastian"
1.1 Leos "Bowser & Peach"
0.3 cats "Beast, Smokey & Thelma"
0.2 Dumbo (non-feeder) rats "Josie & Holly"
0.4.2 fish