You don't have to be rich to vacation down here. You can rent a bungalow for $200 or $300 US dollars a month (or less) and that includes hot water and a kitchen with refrigerator and stove. If you rent by the day or week, it's quite a bit more. Many of the bungalows are a bit run down with peeling paint and whatever but they do have their charms. Most bungalows are in town, about a half mile from the beach. If you are really on a tight budget, you can camp at the beach at one of the ramadas but it's pretty buggy.
Restaurants dinners for tourists
run about $5 to $10 US, but there are some Mexico style places where you can eat for
under $5. Or you can stock up at the market and cook at home. I know people who live on $500 a month.
The buses in Mexico are great but not cheap - fares to Tepic are $5 one way, Vallarta $10, and Guadalajara $20. If you are a senior living here with a permanent visa, you can get a senior discount card and ride the buses for half price.