if you need a chain in a pinch, I don't think you'll find one cheaper than forty bucks in a bike shop. and those are the entry level ones. online, sure I guess you can always find ridiculous deals. so, when diaster strikes, you'll feel the extra cost for sure.

as far as performance goes... sure, there's a difference, but it sounds like you are the type of guy who it won't matter much to. I work on/build/repair/test ride bikes with all manner of shifting every day. from five speed friction in the rear, to eleven speeds in the rear... I can get any shift group art wholesale prices or better... my road bike uses entry level Shimano rsx brifters from the mid nineties... 7 speed. I NEVER miss the "faster, crisper, smoother" shifting of the "nicer" bikes I ride every day. the shift quality of this group is quite frankly nicer than I will ever need, and the only reason I would crave more speeds is if I could not get the right range of gearing for my riding.