depends where you are, in the uk i picked up some cheap digital scales at maplins for £20 - try a seach online
can usually get a hang scale for like $5.. they're good if you're weighing no more than a ounce... actually half ounce.. they get a little off after a half ounce
those little mail scales.... you hold them in the air and clip the baggy to them... i dunno what the actual name is... something like a postal scale or something like that.....
Um if you want any scale I would go for a digital one. I got one on ebay for $40, and it measures down to .00 grams.
i think the black triangle looking hang scales work better than the silver ones with the weight on the end.. seems if the weight gets slightly bent it goes off balance... be sure if you get a hang scale to always check it with a nickle to see that it reads "5" before you weigh anything