It's obvious when comparing an untunable yet adorable craigslist clunker with a high-quality modern piano, but I was surprised to find myself noticing the difference between a $15k grand and a $50k one, too. There was, it must be said, a big difference in age. I wonder how "cheaper" modern Yamahas (the GB1K comes in at a trifling $14k or so, and then there are the uprights...) sound compared to the big grands.
