At this year's AP reading, I was pointed toward dealextreme.com, a Big Lots style online retailer. You can't rely on them to have exactly what you want, but if they do have what you want, it will be cheap.
When I browsed the site last month I found some "portable electronic scales," pictured to the right. Huh... I use crappy spring scales that are easy to break. My set is in need of replacement.
This electronic hook scale doesn't measure in newtons, but does in kilograms (or ounces or pounds or "Jin," whatever those are). The range is up to 20 kg -- way more than I ever need -- and has a 10 g resolution.
Dealextreme sells these for 6.90 apiece, with free shipping. That's much less than I paid for crappy spring scales from a major science supplier last year.
The reader who recommended dealextreme.com warned me to order one of anything before I buy a class set. He said that sometimes the products are defective or just lousy. But because they're so cheap, it's worth the occasional lemon. I bought two of these portable spring scales, and both work fine. I'll set up my opening demonstration next week using these rather than spring scales; I ordered eight more so I'll have a class set for our first laboratory exercise.
Oh, and if these do die in a year, they are no worse than what I ordered from Fischer or Flynn or Sargent-Welch.