If it helps, I found a kitchen scale that measures in grams on Ebay for only $15.00 and it came with a rather large bowl that sits atop the scale (that you could put your snake in). The scale is already calibrated so that you don't have to subtract grams for the bowl.
I just found this one, even cheaper...
http://www.ebay.com/itm/New-2000-2kg...item4d15d0de5e