Nerf War... I need some good tactics

Well I am going to be hosting a nerf war soon and I need some good guns and tactics... There will be teams of five and we have bases (a trampoline with a net and a garage). We have positions like sniper, defense, stealth, ect. I am my team leader and I am going to be under defense. Also I need to know a good place to go for cheap guns, darts, ect.....

~Black Decay