This sounds weird, but I was at Costco with my father and I swung by the jewelry case and was SO surprised at how cheaply you can buy 1.5 carats with good specs (VS1 + F in color for like, $4400!)... Likewise, Tiffany had GORGEOUS rings in their "under $10,000" case.
I hope prices go down a little. I would like to get engaged in the next couple of years, and my SO really wants to get me a nice ring (he doesn't know anyone with a ring smaller than 2 carats, minus other grad students) if he proposes.