Well a handscale (somewhat inaccurate and inconvenient) would run you around 10 dollars. But if you want a digital scale it could be anywhere from about 25-100 dollars depending on what you're looking for. My friend got a pretty decent one for like 30 bucks at a flea market.
www.americanweigh.com thats where I got three of my scales first one got stolen/broke I sold the second one and the third one I still have till this day.