I have driven a C43 AMG for 30,000 miles -- no problems whatsoever except with the pneumatic seat bolsters for the driver's side -- replaced a couple of times by dealer along with reconnecting inflation tubes that also came loose, but seems to be OK now.
Handbuilt AMG engine is flawless -- no drips, seepages, etc. I think there's probably an even higher standard of build quality in the AMG cars, given the individual attention they get and the AMG fanaticism.
Another Charlotte area C43 owner had his cams replaced - always noisy above 2k rpms -- and had lifters replaced to better hold the oil on top of the engine after it sits for a few days. He said that both fixes (by dealer under warranty) corrected the problems. Our local dealer (Beck Imports) usually doesn't cut corners on waranteed work and has been very satisfactory.
True AMG parts are expensive and sometimes have to come from Germany -- front brake rotors are $800 per set, pads $150 per set; I wouldn't want to guess what an individually forged and balanced camshaft or the transmission from the 600 series (sport tuned by AMG) would be.
Tires are also expensive and can be high wear items depending on how you drive -- as the front and back are different sizes, you can't rotate them. I went from the Michelin Pilot Sports to the Sumitomo ZR-IIs (very happy with them) to save some $$.
The center console (heat, A/C, ABS, ESP, electric windows, power locks, power windows, etc.) are standard M-B and no big deal.
If the idea is to "rice-up" a lesser car by bolting on AMG parts (whether or not with a poseur AMG badge :p ), I'd say just bite the bullet and get the real thing -- C36s have become very affordable and are a good introduction to what AMG is all about.
'98 C43 AMG
'93 190E Limited Edition (including factory Sportline package)