Forgive me for posting again, instead of adding to the above post. It seemed bloated enough.
If you are going to use spring airsoft guns, might I recommend a few?
You should check out shortyusa.com which is a very trusted dealer in your approximate area(cheap and fast shipping).
Try to get spring guns with LOCKING SLIDE and OPEN EJECTION PORT for realism. Since lock and load scenes are cool, you'll probably want people to do a lot of bad-ass reloads and slide release stuff.
Here are a few recent models at decent prices with slide lock, open ejection port, and good quality.
http://www.shortyusa.com/airsoft.htm...1&kiosk=&Show=
http://www.shortyusa.com/airsoft.htm...1&kiosk=&Show=
They can be found for similar prices at AirsoftAtlanta.com, maybe even a tad cheaper. I don't know what YOU know about airsoft, but some good trusted brands of spring pistols(on a budget) are KWC, UHC, and UTG.
UTG in particular makes an inexpensive, high quality MK23 SOCOM, if you want to have a joke scene where people make fun of you for trying to use it.
EDIT: Good lord you have got me as excited about this as a kid at Christmas. What's your stance on shotguns?