Price may be the thing that kills the OP's plan (or at least makes it painful). For Shimano rings (as an example) it looks like the cost is around $80 for the pair. I got a CX50 crankset from Jenson USA for that cost not long ago.
On the other hand, switching to 46-34, which is what I'm running on my CX bike for gravel grinding rides, is cheap. You can get and Ultegra 34T ring for around $12.
I would expect that the market for lightly used rings is pretty good, but they might be generally worthless enough that you have to send out a WTB message to get them. I know I've got a pile of chainrings in my garage at any given time.