Thank you for the suggestions. I didn't come back to the thread for a couple of days because I was busy...reading. :D
Cranky, I had forgotten about thrift stores. I've purchased books there while traveling. I try to avoid used book stores because they charge way too much. Library bookstores are also good.
Ixtap, I'll keep my eyes peeled for book swaps when we travel. I have left books in airports before (at the gate area). I always hope a bored traveler picks it up.
And Syonyk...thanks for bringing up Little Free Libraries! I have only used these when I come upon them accidentally, but have found a few gems in them. I'd never used their website to find a location. So I just tried it out, and found one that's along the errand route I'm about to take. I'm going to stop by and drop off a book just for fun and karma.
As for the Amazon options - I've never found anything good on Kindle Unlimited. :( But I just looked at Amazon Prime, and the first thing that popped up was the LOTR trilogy. That's something that I read every few years, and wouldn't want to haul around in paper book mode. So I'll check that next time I'm looking for a good book.
I looked at the daily book deals email today - it goes to my spam folder because I've tried unsuccessfully to unsubscribe. As usual, the only "deals" were 2nd-rate romance books. (I have no problem with 1st-rate romances, but these seem to be the self-published type).
Thanks again for the ideas...if anybody has any more, I'd appreciate it.