I want a scale that handles up to around 2-3lbs (large hardcover). Does anyone have any recommendations (that do not involve stamps.com)? I drive by a PO 3x a week (5x next school year), and so I'm really not interested into postage at home and huge-capacity scales - I just want something that lets me check the PBS weights.

I picked up mine (5lb digital model made by Royal) at Staples for about $12

If you have one near you I've also seen cheaper models at Harbor Freight.

I got a good digital scale that can handle up to 75 lbs. off of eBay. I paid about $10.00 shipped. I have had it for a little over three years now. I had to change the battery once. That and dusting it are the only maintenance I have given it. It did come with an A/C power cord. I just don't use it.

I too just got a nice 50 lb. digital scale on eBay (my 5 lb scale wasn't big enough for some packages I mail out)

I got it for a whopping 98 cents, and $16 s&h and I'm quite pleased with it.  It's got a .2 ounce (two tenths of an ounce) accuracy so it's working fine for both letters and packages.