Since the size and shape are relatively simple, I'd fabricate it out of pvc, wood, and aluminum bits. I've built accurate copies of Greedo's blaster and Princess Leia's blaster for my gf and I this Halloween, and know that it can be done. Just know going into it that it won't be quick and easy. Take your time, pay attention to the details, and you'd be surprised what you can build yourself.
I weighted both blasters I built with coins so that they'd be more convincing when they're picked up. It also helped to balance them.