Try your local headshop, or do a search for digi scales online here.

If you have the store called The Source, used to be called Radio Shack, they sell a nice little digi scale for $25 I think it was. I don't know all the details, but I believe it had a 250gram limit.

I got mine from a this shitty pawn shop back in Alberta. This guy had like VCR's with $ tags saying $90 and shit. It was so outdated, but by the front counter he had this bong/pipe case. I saw a scale there and gave him $25 for it.

It works, but it likes to shut off by itself after about 20 seconds of no use. You get what you pay for I guess, and the instructions are all in Korean, so yeah.