Frugal and Energy Efficient Living

To answer your question about cost of living. No, in either Belize or Mexico, the cost of living is not high, even in tourist areas. For example, we stayed with a Canadian couple in Belize. They have a beautiful home, with pool and a couple of rooms they rent, B&B style. Their monthly expenditure, including everything, car insurance, taxes, food, utilities, transportation etc. is $400 USD.
Where we are currently, in La Cruz de Huanacaxtle, a small fishing village about 15 miles north of Puerto Vallarta, you can rent a 1 or 2 bedroom apartment for about $300/month, utilities, A/C and internet included. But it is hot here in the summer, 80's and 90's. We just spent 3 nights visiting friends in Chapala, which has a very temperate climate, averaging in the low 70's year round. I have a friend who has been there for 5 years, living on $700/month social security. His 1BR apartment is lovely and costs $200/mo in the best part of town.
Nice 3BR homes start at around $80,000 in tourist areas, but the sky is the limit, like anywhere else.

Food is really inexpensive, especially if you prepare your own meals, or eat where the locals eat. Tourists who want to eat the crap they eat back home will pay more. There is always a market for suckers who want to drink coffee at Starbucks, or buy time-shares. Occasionally, we splurge and eat out in a fine restaurant, where you will be hard put to spend more than $30/person, including wine and cocktails. Language should not be an issue. Rudimentary Spanish goes a long way, if you make an effort.
Feel free to ask for more info.