La Casona Real is only about $35 a night. QUOTE]
$85.00 Low Season, $100.00 High Season, less 50% during May, Sept. and Oct. (per their site).
Hotel Mary Carmen looks like it could be had for &29.00 per night --- no prices on their website, but went to Trip Advisor, and from there to Hotels.com. and that was the price quoted. I don't trust Hotels.com as far as I could throw them, but worth a shot.
We've stayed at Hotel Caribe on Calle 2 Norte between 15th & 20th. The rooms are very basic, but spotlessly clean,ac works, and they have a better than adequate pool. Very quiet.
The website they had no longer exists, but I'd guess that you'd be able to get a room even during high season. Again, a guess, but I'd imagine price would be in the $50.00/nite range.
Found a link for email communication:
https://www.zonaturistica.com/en/hotel/20822/caribe-cozumel.html
They have rooms with 1, 2, and 3 beds, with complimentary pastries and coffee in the mornings.