Hopefully you paid under $2,500 or so for that projector, or you paid a bit much for what you got.
The mount is likely non-extendable unless it uses standard 1.5" threaded pipe. There are a ton of different mounts on the market, but I strongly recommend only the Chief RPMAU series of mounts. They are incredibly stable, yet incredibly easy to aim and setup properly in a home theater. A bit pricey at about $160 online for the mount, and you still will need a mounting flange and a pipe extension, but both of those items can come from your local hardware store (with a can of flat black spray paint).
I rarely recommend the impulse projector buy, but the 8700/9700 projector from Epson is of very good quality.