i suggest a digital scale. There was one that radio shack had on clearance not too long ago (back in feb.) for something like $10. the only prob with it was that it has to be plugged into a computer to use it; it didnt have a display on it that told you the weight.
There's an ebay seller that many people I know have bought from - OldWillKnot. Has competitive prices. Tip: make sure the scale you get has an AC adapter and is in compliance with USPS specs. (needs to weigh in 0.1 ounce increments). I have an UltraShip scale that's been real good and those come with a lifetime manufacturer warranty for people in U.S., 30yr for international customers.
off ebay site: http://www.oldwillknottscales.com/
ebay store: http://stores.ebay.com/www-OLDWILLKNOTT-com
BTW, if you're located in oklahoma might want to find a different seller. OldWillKnot is in Oklahoma and thus has to collect sales tax for buyers in Oklahoma.