Darn, I can't stop posting! You mentioned getting a Gemmy. I'm not a big fan of the Gemmy screen. I've only seen one in person, but I was unimpressed. I know a lot of people like them, so I'm probably in the minority.
I've been looking for an inflatable screen alternative, hopefully something that I could "rent" to customers more like a "drop and go" package. I found an interesting screen made by Camp Chef. Looks neat, goes together in about 15 minutes if I understand correctly.
Target has it for $199, but I've seen it for less. Here's Target's ad:
http://www.target.com/gp/detail.html/191-0107722-5089868?asin=B0033SC2SE&AFID=Froogle_df&LNM=|B0033 SC2SE&CPNG=electronics&ci_src=14110944&ci_sku=B003 3SC2SE&ref=tgt_adv_XSG10001
And here's a youtube video explaining the set up: