I used to shoot Highpower and wanted to get back to shooting rifles after a long stretch at a club that doesn't allow centerfire rifle, so I finally convinced my husband to let me sign us up at a club that has Highpower/CMP matches. I shot the last match shooting one of the clubs Garands, and I really would rather go with an AR - the Garand just seemed unweildly to me, and the guys shooting the ARs seemed to have an edge. My husband of course would prefer I go with the Garand because of the cost through the CMP, but I think I could convince him to let me go for the AR if I built one from a parts kit, which would save on the cost considerably (I have built other rifles/pistols in the past, and have a top notch armorer who is willing to help me along). This would primarily be for the CMP matches, but also possibly some 3-gun events.

I know I want:

20" SS Heavy barrel
Free Float Tube
National Match Front/Rear sights (could get this as a later addition to save on cost as needed)
Two Stage competition trigger (could get this as a later addition to save on cost as needed)

Which online dealer is going to be the best for me to go with to get a decent price/good product? I am not as concerned with name as I am the quality of the parts, and getting a good value.

I'd recommend White Oak Precision (http://www.whiteoakprecision.com/) and/or White Oak Armament (http://www.whiteoakarmament.com/).  You could have a rifle that would take you as far as you want  to go if you get an upper with John Holliger's modified sight and a lower with his tuned RRA trigger.  A barrrel set up by John is first rate, and you could do the rest of the assembly yourself using generic parts.  I've used John's work on may spacegun and can recommend him wholeheartedly.  His tuned trigger is the gold standard for service rifles.

I just ordered a White Oak Armament cmp upper with the White Oak Precision pinned rear sight, a set of weights, and a RRA NM lower with a White Oak Precision tuned trigger.  Overall Cost was pretty low and I don't think you can get a better rifle without going straight to John Holliger.  I ordered the upper from WOA directly and going to get the lower from Adco.

My brother shoots a Rock River Arms National Match, and it's a damn nice rifle and cost about $300 less than I spent.  That's probably a better price/product ratio and would suit your need better.  If you feel the RRA NM is letting you down you can send it to White Oak and get it tuned.