Welcome! I too own a former rental (Cruise America) RV with over 125k miles and am very happy! Good luck to the OP.
As for rentals being priced as high as new ones, that was not my experience. Mine cost 40k less than a new comparable model and there isn't a single thing wrong with it. It looks better than anything any private seller had to offer in my area and it was way cheaper too. They even let me spend 8 hours with the guy who gets the RV's ready for delivery. 8 hours later I had a list of 42 things I wanted replaced or addressed from mechanical to coach. They took care of everyone without complaint. That 8 hours cost them about 4k. Honestly I was shocked by how positive the experience was. Given the insanely bad reviews Cruise America gets online from their renters, I avoided the place for two years while searching for a used RV deal.
But yes, it is hard to find a good and affordable used RV anywhere and especially in California. Two types of people in California. Those who own an RV and those who want to buy an RV. Everybody here camps and no surprise given the options from Yosemite to Big Sur and the list goes on and on and on....
I had a nice experience with El Monte when I visited them. They seemed like decent folks here in LA too but there inventory was at the time small and out of my price range.
Another option is Road Bear. They sell their barely used rental RV's with about 20k miles on them for about 6-7k less than new prices.