I guess Im to minimalist for that. I wouldn't spend 5k on jewelry, car parts, or tools (unless my lively hood had to have the tools). Just like I wouldn't spend 2k+ for a handgun.
If accuracy is that large of a factor, why not just purchase a Wilson Combat barrel and drop into your RIA? Cost of the RIA: 350. Wilson Combat barrel (which can be purchased anytime): $200. So you've invested $550. By my calculations, you're still 2,150 in the black. Once again, to each his own.
You'll find many on here thats going to swear that the higher end, custom built gun is the greatest thing out there. I know people who own Kimber, Para, Springfield, Taurus, and RIA. Out of them, the only ones I know that have had zero problems are the "lower" end of that group. Funny that many will sing the praises of high end 1911s, but its been my observation that the lower end has held together and had zero problems compared to the "top o' the line" brands. Thats why if I ever go 1911 again, it would be a Springer GI or RIA. Ill fine tune it to my preference as I go and have money left over to boot.
It's not as simple as putting a high grade barrel into a base unit and expecting high end results. Sure, it will likely improve, but putting a Ferrari engine into a Toyota will give you limited returns in overall performance.
Most of the guns on the market are made of a conglomeration of parts, from weakest to strongest:
MIM - Metal Injection Molded (Metal Powder and Epoxy/Resin baked in a mold)
Disconnectors, slide stops, grip safety, trigger assemblies, fire components, etc.
Cast Parts - Metal cast as a liquid into a molded shape
Forged Parts - Forged and hammered at high heat to a general profile, then milled to shape (think black-smithing)
Billet - CNC machined to spec
A lot of guys will buy Kimbers and Springfields which contain a ton of MIM parts. A Sig 1911 at $850 has far fewer MIM parts than a Springfield or Kimber's in the $1400 range. The Sig is mostly American made, and some parts are German or Austrian. The Springfield frames are all made in Brazil. RIA's are made in the Philippines. Most guys will buy cheap 1911's and replace the high wear / vital components with aftermarket billet parts from Wilson and other companies. You can build a really nice gun this way that will be a pretty accurate and comfortable shooter.
Wilson's high end guns are made with their "bulletproof" line of parts. The entire gun is milled from billet stock. It's the highest strength available, and the entire gun is assembled and hand fitted by some of the best gunsmiths in the industry. Les Baer, Nighthawk, STI, Ed Brown, and many of the high end companies fit their guns the same way, but Wilson is the only one that offers an all billet produced gun, and guns produced with all in house produced parts.
Even if you took a bunch of aftermarket parts and fitted them to a RIA or Llama frame, the gun may perform better, but it won't be as precise as a gun original milled and speced to work with those parts to begin with.
Wilson offers a few different options, some of which include non-billet parts. The Wilson CQB is an amazing gun, but you pick up a Supergrade and the feeling is obvious. Everything is smoother, slicker, tighter, and the gun just feels different. It's like going from an A to an A+.
Guns are like cars, an entry level car will get you to your destination, just like a higher end car, but sometimes the higher end car runs smoother, more comfortably, has more options, and is hand fitted for longevity, kind of like buying an old Mercedes.
The point is that you don't have to spend a lot of money to buy a reliable gun, i.e. Glocks, but spending a lot of money will often result in getting a hand made, hand fitted, hand tuned, custom sized, piece of machinery without compare. After shooting a high end piece, you'd be unlikely to ever want to carry anything else. Until you've spent some time shooting one, you won't know what you're missing. They aren't for everyone though, different strokes for different folks.