Unfurnished you can get a place like that from any thing between 10-20 K per month..
Most houses here are not built with the hot climate in mind and they often need to be air conditioned..
If thats the case add say 15.00 Peso per every hour you need to run it.
The average bill for our tenants is about 3k per month but we have some Yanks that have bills over 8K!!
3 k is a pretty doable figure..
A weeks shopping can be cheaper than the UK on average as long as you stay away from the imported isles at the mall!!