your local dope store,lol.Ah,head shops carry the small digi ones but not sure how heavy they go,probably not for larger snakes so maybe one of those for smaller measurments and then just a regular digi for humans from target or something.Im sure someone knows something better,good luck.
lol, you go in a head shop and ask for the biggest scale, then the ask what your dealing and you say... BOAS!
no srsly i actually really want one but i dont think my moms cool with me getting a scale because she knows a bit too much...lol