I have never been to show where I have felt it wasn't worth the admission (and associated) costs. From $7 for a local guild show to spending the week in Houston, I have always been inspired, learned a lot, and met wonderful people. I think the comparison to other outings is valid, concerts and sports events are big ticket items as well.
And knowing what the costs are just for our small town guild show, I can just imagine the overhead costs in running a large regional show!