A lot of the POS (point of sale) monitors don't have a standard VGA connector - they connect to a POS system via a proprietary cable. It's a catch to look out for.

I have a stash of 9" B&W CRT VGA POS (LMNOPQRSTUV) monitors that do 800x600, and one colour 10" one. No, they're not for sale, and besides shipping is a biotch