A lot of Jameco's parts are cheaper than you'll find most places. Their "Valuepro" blank label rectangular and DSUB connectors, for example, are a much welcomed relief from high prices for Amp and Molex connectors. I've been buying resistor packs from them forever. And what semiconductors they do have, are often reasonably priced too.
Of course the main draw for me is that they're a couple miles down the road, and I can order up components and walk in 1/2 hour later to get them.
And Osgeld: as for hanging up after you refused to pay the quoted shipping and said you would never buy anything from them, what did you expect? You called them to complain over a matter of probably less than 12 dollars, most of which they would be paying back out into shipping. The person on the phone obviously realized an incompatibility and decided not to waste more of everyone's time. You told them you weren't a future customer: conversation over.
They do actually have a USPS option but it's not any cheaper than the rest.
Before I lived close enough to to walk-ins I still ordered from them, but it's always been easy for me to pile up a big enough order that the shipping price makes more sense.