If you really want to get some enjoyment, get a base-model Colt .45, and start from scratch. You can build a $2k Wilson Combat .45 for about half the price. That's what I did. Only the frame and slide are original colt, nothing else, and the frame and slide are modified.

I did the same, twice. First one was an AMT Stainless Steel "Hardballer". Really cheap 1911 clone pistol, but the frame and slide were the only parts that were used in the finished pistol (finished pistol ended up chambered in 400CorBon) Second time was with a bare Essex frame and a Caspian slide (Still have that one, though it has a Ceiner 22cal conversion on it most of the time). In both example, you can build a slick, functional, 1911 for far less than what the custom guns retail for. Personally, I shoot a stainless steel Colt GCT with no mods other than a heavier trigger spring (the stock Colt spring made the gun double on anything other than light target loads.)

As to the 50AE, 500S&W, 454 etc. I personally wouldn't go out and buy one. I took one in on trade, but really, these are pistols with damn little functional use to them. They are pistols big enough to try to do the job of a rifle, but a rifle is always going to be better at it.