I really hate being jostled all the time so I don't generally turn up until 9:00 - 9:30. I probably miss some things that I want but there is usually something to make me happy. As I was walking in this year I saw a guy with three process lenses on a board, but I didn't stop to ask what they were or how much he paid. Last time it was a 5x7 Graflex SLR that sold as I was walking toward the table. Again, I didn't ask how much.
I take about $400 with me, just in case I see something I really need. This year I wanted a tripod (and got it) and wanted 8x10 holders and there were none to be seen. I find that most of the lenses are too expensive compared to eBay (including shipping costs) but the other stuff tends to be cheap. I've bought four of the Graflex style grafmatics at Camberwell and paid around $25 each while one I have bought on eBay was closer to $60 - plus postage.
I try really hard not to collect cameras, so I focus on buying 'needful things' rather than things that take my fancy. Next time could be a little harder as I've managed to get most of what I need, but there is always lenscaps, film and paper.