If you are looking for non-firing weapons to use as decorations, look at the airsoft guns available now. The main reason for us in gun-friendly states using them is the cost, for y'all in unfriendly states, it may be the only acceptable way to go.
I bought a really nice airsoft M60 MG for less than $400. Looks very much like the real gun (and I used to be an M60 gunner). Only weighs about 14#, but that is not a bad thing! When you are looking for three of them, like Quonsethut was for his gun truck, cost is a big issue.
I also needed an M79 for the V100, got a realistic one of those for about $150. That one (CAW) was on sale, I think they are usually something like $240, metal frame and wood furniture. There is a less expensive all PVC version too.
Both came from AirsoftGI.com They have some really nice looking M14s, and just about any other military rifle/pistol you can think of.
Cheers