My small "review" (for lack of a better term) of the 12 ft inflatable screen that is made by Gemmy. I got mine through Target.com for $187 on sale with free shipping. I ordered it on a Monday and did not receive it until the following Tuesday so 8 day delivery if you can wait that long. I think the screen is great so far.
UPDATE: Okay, so it's now the end of August and I have used the screen almost every weekend since I got it (about 2 months). The set-up and take-down process has gotten much faster the more I use it & I have found that most of the time I can get away with just the longer tethers attached to the top of the screen and I don't bother with any of the other ones. However, that being said, if there is any wind then you better use the middle tethers AND the stakes. I had the screen set up at a beach house about 2 weeks ago and it got very windy halfway through the movie and the screen had a hard time staying straight with just the top tethers attached. I also found that keeping the tethers (all 8 of them) individually wrapped and then I keep them separated in 2 different bags marked "long" (for the long ones) & "short" (for the short ones) makes for a much faster setup the next time around. Just putting them all together in the original bag makes for a huge rats-nest that will take you at least 15 minutes to undo. I would not recommend setting the screen up on any paved surface. The material the inflatable part is made of is very thin and if it accidentally drags under one of the fans it WILL rip so try to set it up on a "soft" surface like grass/lawn.
I use a BenQ MX660P projector which you can get on Amazon for about $470 and it works GREAT!! I use my PS3 as my video source, both Blu-Ray's AND regular DVD's look great on this set up. I usually play video games with my friends while we are waiting for our wives & Gf's to get situated before the movie and the games are like new games when you're playing them on a 12' screen!! The go-to game lately is Need For Speed:The Run. I have yet to hook up the Wii but it's on my list of things to try. The only downsides to the whole process (here in CT anyway) is now that the summer is coming to an end by the time that the movie is over around 11pm or so EVERYTHING is covered in dew. I don't want to put the screen away wet so I usually bring it into the garage or basement and then bring it out in the sun the next day for about 10-15 minutes to dry out. The material is very thin and it drys out pretty quick. I roll the screen onto a 6 or 7 foot piece of 2" PVC pipe to keep the wrinkles out but this makes storing the screen kind of a pain. The inflatable part fits snugly back into the bag it came in even though it doesn't seem that it will ever go back in there once you pull it out. I'm still super happy with the screen set up and all my neighbors love it. I live on a corner & I have a small back yard that can be seen from the stop sign in the street. people walking by and cars at the stop sign always love the set up and some come over and talk to us (kind of a pain while you're in the middle of a movie) so it's a good way to meet new people :) Feel free to post any questions and I'll try to answer them as best I can.
UPDATE: 12-24-2012
In response to todays comment:
You tube will not let me post links in a reply so I had to put it here. I did a lot of shopping before I got a Ben-Q MX660P. The first one I bought did start to make a noise about 2 weeks after I got it, it still worked great but made a fan noise. I emailed Amazon and they overnighted a brand new one along with a return label for the old one so I was up and running the very next day. I have 0 complaints about my Ben-Q but 31' is a long way for a projector & you might have some problems finding one for that distance that will fit this screen. There's a lot of great sites to check out & see what other people do, I'm a big fan of backyardtheater.com & I also used ProjectorCentral.com for research. In the end it's up to your needs & BUDGET. I like to do things as inexpensive as absolutely possible without sacrificing quality!
I have been using a Klipsch 5.1 Promedia system that I bought years ago for my desktop but I was no longer using. They are now discontinued but I think you can still find them floating around the internet. I absolutely recommend them 100%! They sound awesome, have a GREAT amount of bass, they're extremely portable and the sound does not carry throughout the entire neighborhood. They have a small module for volume/bass control that is on a 6-8ft cord that I keep right at the base of my seat so if the movie has parts that get a little loud I have full control to turn it up & down as needed. The system I am talking about is here: http://www.youtube.com/watch?v=gQkjyehHUZM Good Luck and welcome to the club!!