I recently bought this scale on eBay and it seems like such a great deal that I figured I'd post about it:
The scale was $3.99 Buy It Now plus $8 shipping to Canada. There are a bunch more on eBay if you do a search. I think shipping is less for USA residents.
I got the version that reads up to 2000g, but you can get them 500g and probably 1000g versions. 2000g was perfect for me since some of my stuff (ie. tent) is over 1000g. Search on eBay for '2000g digital pocket scales'.
I got the scale 2 days ago and I've been really impressed with it. A bunch of my gear I weighed last summer using an expensive scale at work. Using this scale, basically everything is reading exactly the same (to the gram).
The surface that you set stuff on is a bit small, but I found this easy to overcome. For bulky stuff (ie. packs) I just hang a clothes hanger on the scale, zero the scale and then put the pack on the hanger. The hanger method works good and so does setting something like a Nalgene on the scale to raise up the platform so you can set droopy stuff on it (ie. clothes).
Here's a few more for sale: