If I were you, I would do one of two things: Either buy a nice rifle like an AR15 or get a high end pistol.
For example I would get a nice AR15 M4 Carbine as those are very easy to build and customize.
OR
You can get a nice pistol like a Kimber or Colt 1911, or HK USP etc.
Those would be my suggestions. of course, it would depend on what you're into in regards to firearms.