I have never been charged 'postage' when I pick up in person, but they do charge a $7 handling fee for up to 10 items (I think) when you pick up in person. I've never had them ship anything to me, so I can't speak for them shipping things.
As for items not matching on screen, they will get several of the same prop sometimes, and photograph one and re-sell it many times. So you won't always get the one photographed (this usually only applies to eBay, not the live auctions). They had a book I wanted from 1408, and I wanted to make sure I got the one used on screen, so I asked them to bring them all out. They had no problem with that, and brought out a stack of books, and I found the one I wanted. Of course they were all production made, but I wanted one I could match onscreen.
They are doing a live Underworld 3 auction on the 7th... Should be fun.
The one thing that has probably prevented me from having a bad experience with them is that I attend the auctions in person (and can thus see the items before I bid on them), and then carry them home myself. Usually no need for customer service (all though they always seem nice to me...), and no shipping, so I can't really speak for those two aspects of the company...