Tiko, I did just that-- got an SA 1911 GI and then added stuff. So far, I've put sights (Novak fiber optic), hammer, beavertail, extended slide stop, extended thumb safety, Pearce grips w/finger grooves, extractor, and a flat mainspring housing (snakeskin) on it. It would have been cheaper to have just bought a fancier one to start with, but then I wouldn't have had the fun I got to have.
As to accuracy, I don't find the thing to be all that great at any distance over ten yards. Might be time for me to think about a match barrel/bushing kit. ;-)
Something to think about: Lurper let me shoot his Taurus 1911 when I did a session with him, and I was really impressed with it. For around $600, it's already got most of the stuff I like, right out of the box. 'Course, I didn't know what-all I wanted on the gun before I got mine...