If someone asks you how much it will cost, ask them what they would be prepared to pay. This is logical, if unsure about what price to charge tell of the equiptment you have and then compare to studios around that you know (prices and eqiptment comparisons-ie the downsides of their set-up comparative to yours).
What I do is say, "look here you are getting...........at such and such a studio you would be paying....an hour, also....for an engineer, here you will get....(tell them about the set-up0". Then tell them of what you hacve to offer including if you will 'master' their music, then get them in a position to offer you a price (you should then interpret their offer which should now be realistic and adjourn what price you would except-usually marginally above the offer). It's all a game, in most cases unless proffesional, a band will want to record in a home studio rather than a hi-tech one as they will feel a little un-easy.m Sell it to them-play every situatuation as it comes-I don't have first hand of the Mexico market either-these are just guidelines.