I have this one, and it works fantastic for me - but my BP's are still babies.
http://www.amazon.com/Camry-Accuracy.../dp/B00A8RMWEW
$18 on Amazon.
The bowl that comes with it is perfect for babies. However, it's way too small for adults, so I just went out and grabbed a big metal mixing bowl to check it. Weighed a Webster's Desktop Reference set in the small bowl - 1.73 Kg. Put the large bowl on and tared it out, and the set weighed in exactly the same. That big bowl should be plenty large enough for any ball python - not so much a mature Burmese, probably!