Stop by a grocery store with a Bulk Goods section and ask to use their scale for a moment?
Pick up a cheap battery powered scale at your local Smoke Shop for $15?
Are you in a place with NO other homebrewers that you could borrow a scale from?
Do you have any neighbors that bake bread or pastries? Some folks follow the Alton Brown school of biscuitry and weigh their goods, not measure them. Maybe you can borrow someone's kitchen scale?
Borderline unethical, but... buy one at Bed Bath & Beyond, use it quickly, and return it saying that you bought the wrong one for your mom who wanted one for christmas??
I don't know if I'd trust eyeballing on hops... at least for the bittering or mid-boil additions.
I suppose that, if I was trying to measure out flame-out hops, then okay, I could see eyeballing that. In that case, I'd say a half-full paper Dixie cup of the smallest size (the 2oz bathroom cup size).