Ask locals for a house to rent. The W side is cheaper as there it is where the locals live. Many houses are rented only for holidays, so bargain hard.
Kaaxan Vacation rental
(http://www.kaaxan.com) gathers many options for vacation rentals in progreso, and around.
Hotel Casa Isidora
Calle 21 no. 116 entre between calles 58 y 60, col. ismael garcia 52 969 935-4595. (http://www.casaisidora.co...) rooms with 2 double beds, us$55 including continental breakfast.