Congrats on getting out. I've been in three years and just commissioned, so I'm extending about five years. Best of luck with you and shopping around. My advice, even with the G.I. Bill, you won't have what money you've saved for long. It goes away even faster than it comes in.
Depending on how much you ahve and what you plan on doing with your stang, you might want to look into a used 99-09 model mustang. I've found that the parts are plentiful, the costs are low, and they look great on the road. I've had two 2000 mustangs and they both have served me well. Other people have their opinions and facts to back them up, but I love my 99-04 generation mustang.
Since they are a bit older, their cost isn't too bad and you can still get a GT in good condition. Do a ton of research on this forum and look into what people have said about their year mustang, the pro's and con's of their stang, and take your time. These cars aren't going anywhere anytime soon.
I'd also look into the Bullitt mustangs. They look great, sound amazing, and I've always been a fan. You can even find them on the strip sometimes.
Best of luck to you, and PM me if you have any questions.
also, what do you mean by you're going into sam? or did I miss something?