There is still guys out there holding onto their pinned A2 uppers with NM float tubes. A WTB ad at the National match forums will net you one pretty quick. They usually sell for $400-500 for the complete upper. It is the fastest and cheapest way to get started in the sport.
For a person developing their skill, pinned and 1/4 MOA sights is not needed. You can be competitive with just a NM hooded aperture and NM front sight post. Most that get into the sport will likely be going to a WOA, Leupold or NF service rifle scope.
You can buy a 1/2 Moa hooded NM aperture and windage screw from CLE and convert a standard A2 or carry handle for about $40. It is a simple parts change out. I bought the proper size tap and now drill and thread the battle aperture for the CLE hooded aperture. I have converted 4 this way.
In this sport, buy the best equipment. Used if you have to. Some of us learned the expensive way and bought cheap rifle scopes, scope stands and spotting scopes just to spend more money to upgrade later.