Here is one of the best bangs for you buck, I think:
http://www.adorama.com/LTU60BC.html
Beautiful, big and 35 bucks. This will do full length on 3 or 4 people, easily. You may want the plastic diffuser on the flash just to help spread the light in the umbrella. Quality is there, I bought a couple of brolly's cheap off ebay and now regret it, they have started to fall apart and have had little use, so make sure you get something cheap, but sturdy.
This umbrella wont work well in low ceilings, but may be perfect where you are going to shoot, and they ship fast so you'll have some play time.
LOL, great minds, posted the same time as toolman21 above.
and I want to add, get a stand that is sturdy - these are a bit heavy, and a small footprint stand might have issues, I've used them on this stand and been fine:
http://www.ebay.com …_trksid=p3984.m1438.l2649
Godox/Flashpoint r2 system, plus some canon stuff.