In Cuba, the best is to live at so-called `private house`. Prices are not so lows because they can not officially rent more than 2 rooms (of course, rents are more) and some pay huge fees. In Havana I paid 25 USD, 15 USD in Trinidad and in Remedios 20 USD. The houses are generally in very good conditions, some true architectural jewels.
But you can also try the 5 Stars hotels, wich are amazing.