I was in similar situation recently, trying to keep to genuine Shimano parts (which I usually got in a good shape and at a decent price). The thing is, that looking at various chainrings, there isn't that much of a difference, quality-wise. Granted, my sample isn't exactly extensive, I could compare Stronglight, Peugeot, Shimano and Ofmega. I don't know about the modern, carbon fiber / titanium bicycles, because I don't have one, but looking at various parts from the 80's, it seems that it's just a chunk of aluminium designed to be replaced every now and then. It appears to me that any known manufacturer with any kind of quality control will produce chainrings of similar quality. I did have a freewheel which shattered during my first ride using it, so it seems things can go badly even with simple parts, but it's generally not a problem to get a refund if that happens.