I thank you for your service!
Now lets get real. Traveling is expensive! Staying is expensive. To put it bluntly, RVing is expensive. Now, can you do it on the cheap? Yes you can; but you have to plan and have a good plan.
If you're not mechanically inclined I would suggest you get a professional to look the unit over you want to buy.
Don't get into a hurry on buying something. There is tons of junk out there and very few good units. It will take time to find a good one.
Good luck and have fun.
By the way, did I thank you for your service? If not, thank you!