I've been building and modifying 1911s for a good many years. Most of my customers start combat or bullseye shooting with a standard production gun. Like Mickey says, after they get better than the gun, they will start having modifications done.
A good trigger is a must. 3.5~4 lb with no creep is the most desired. Many organized competition groups have limits on trigger pull so you have to stay within their standards. Unless your gun has a defect, there's no reason to replace parts for a good trigger job.
Next is sights. Combat shooters like the 3-dot systems and bullseye shooters hate them. Most new shooters want adjustable rear sights, the old timers want fixed rear sights. Once the fixed sights are registered, the shooter uses a "hold over" for 50 yard targets. So save yourself the grief and have a good set of fixed target sights installed.
The most critical accuracy modification is the barrel. I use Kart barrels and match bushings. Both parts must be fitted to the slide for a real solid lock-up. The top end functions as a solid unit. This means the barrel hood must lock into the breach face with minimal movement. The bushing must be very tight in the slide and the barrel must fit the bushing very snug. Actually, the frame-to-slide fit does nothing for accuracy unless it's real loose.
Some other typical "good" mods are: custom grips, beavertail grip safety, and a trigger that matches your finger length. These parts might total $100 and maybe a few bucks to have the trigger fitted.
The barrel, bushing, and sights will cost about $200. A trigger job, and the gunsmithing required to mount sights and fit the barrel can run as high as $200. The rest of the frufoo stuff is just that. You can spend a lot of money on non-value added modifications that don't do a thing for accuracy or function except bragging rights.
So for about $500, you can make an excellent bullseye or combat gun from most any quality 1911 platform. I would avoid foreign made guns with the exception of Springfields Armory. The Norinco, Charles Daly, and Rock River have poor metallurgy and will wear out with competition type shooting.