There's a place in Denver called Packrat Antiques that has great science antiques. There's an old man who runs it who is notoriously rude. My experience matched most of the negative reviews you'll find here:
http://local.yahoo.com/info-19606029...ntiques-denver
and here:
http://www.yelp.com/biz/packrat-anti...NnG8feYRTpEWeQ
I was looking at slide rules and when I didn't buy one he said, You just wasted 45 minutes of my time! Don't hurry back!
(I feel like I've posted this before.)