I'm getting a cheap scale that I don't really trust a huge amount, so is there any leeway when dosing out 2cb? Also what's the typical dose, 20 mg?

For a cheap scale you're probably not talking about a little inaccuracy at the mg range. You're more talking about taking 2-3 times the reccomended dose.

do you have a better way to dose it out? because there's no way i'm buying an expensive scale, i just don't have the money. Also I don't know how much I have right now so I couldn't water dose it.

you'll be fine with a 0.01g accuracy scale. now how long for tolerance to go down for 2c-b?

Take 10x your dose and divide that out. You could do this twice so that if you were to take 20mg you could weight it out to 2g (though I doubt you have that much) and divide that. You could also try it with solubilities in say, ethanol, but that would require small mL measurements which you may not have access to (though I have a 1.5-foot long 10mL pipet that works amazingly for such purposes; pretty easy to get).