There are plenty of good trailers on CL that don't have to be a military one. Quite frankly the military stuff is awesome and literally bomb proof but why not build something to suit your needs for cheaper or the same price in the end. The nice thing about getting a common size 4x6 or 4x8 or what ever trailer is you can buy common up grades for them with out breaking the bank on M416, or what ever, specific parts.
I picked up an American Made Haulin tilt 4x8 trailer on CL for 325 bucks locally. Its got a 2,500 pound capacity and the frame is boxed, not C channel and everything is welded (no bolts to rattle loose) its solid. I have some 31's including a spare I'm going to throw on it once I order a wider axle with 5 on 4.5 lugs. I already made a great header rack for it and ditched the wood sides. It holds 3 motorcycles like a champ. Tons of tie downs and I added LED lighting. Next I'm going to make a removable rack for a RTT and awning, fenders suited for the bigger tires and maybe sides...I'm trying to keep mine as a dual use camping/I don't have a truck kind of trailer. Non the less, trailer, steel, hardware, wheels/tires, axle and so on I'll be in it for probably 800ish bucks!
I look forward to pictures and a build thread when you get yours figured out! Good luck.