Sorry, I spent 20 minutes searching for Pesos on this forum without finding an exchange, so any posts would be helpful!
There are occasionally individual offers to do trades, like this:
- https://bitcointalksearch.org/topic/vendo-bitcoins-mexico-74474
As with any person-to-person, over-the-counter trade, know:
- http://wiki.bitcoin-otc.com/wiki/Using_bitcoin-otc#Risk_of_fraud
- http://blockchain.info/wallet/sms-phone-deposits
If you are a merchant, you can set up with Bit-Pay to have your customer pay you online using Bitcoins and then those are converted to MXN and sent to your bank account.
- https://bitcointalksearch.org/topic/ann-bit-pay-expands-direct-deposit-to-canada-and-mexico-lower-fees-for-usa-69425
VirWoX accepts PaySafeCard, though I don't know if the PSC purchased in Mexico is denominated in USD or if VirWoX can accept a PSC with MXN on it.
- https://www.virwox.com
- http://en.bitcoin.it/wiki/VirWoX
There is also a cross-border mobile payment system called Boom from M-Via. Perhaps there is a family member or friend in which Boom can be used to send funds from Mexico to that person who has more access to easier methods for purchase of Bitcoin.
There were individuals willing to do trades as well:
- http://en.bitcoin.it/wiki/Category:Local
If you learn anything useful or a new method, please report back!