Bathroom scales would work for that if you don't need anything super precise. For about $200 or so you can get small platform scales that run off of either batteries or a 110V plug-in (works off an inverter in the lighter) that comes with a remote display head, reads in lbs. or kgs. (handy in Canada), and actually takes quite a bit of abuse. It definitely does help the impression you make on some customers, compared to either a bathroom scale or guessing at weights.