Become freindly with you local cinmea equipment supply compnay and see what they have for used equipment. Pardon the plugs, but I'm in Oregon and I use American Cinema Equipment (Portland, OR) becuase they have rooms of used equipment and they respond very quickly to any technical problems i'm having. Cin Tronics in Everett, WA has been great at finding the esoteric equipment i sometimes need.
It is best to establish a relationship with a supplier who you can trust. they will know you and your equipment and can help out. you're going to be dealing with them eventually and it makes 'em much more cooperative if you bought your equipment from them in the first place. The difference between refunding a show and making a deposit will depend on whether your supplier is willing to take your call at 9pm on sunday.
BTW, I'm my place i use a good ol' Strong lamp and power supply, Motograph AA projection head and RCA 9030 sound head. in three years i have never had a problem that has shut me down. They take a little more care than some, but keep on tickin' . . . .