Short term Internet?

[WRT]

Great info on the TP Link 703N Mini Router. That would work well with a IUSACELL sim .

IUSACELL works best in the Guanajuato area.

I use a iUSACELL pay as you go plan with unlimited sms and calls, and the 4GB data for $699 pesos which is similar to the $50 USD T-Mobile plan from the USA.
http://www.iusacell.com.mx/libertad/

You can insert the the iUSACELL chip in your smartphone and tether the wifi to your other devices.

Also try downloading the Wi-Finder app.

Be careful with Tel Cel they are sneaky thieves and good luck trying to get out of a contract with those clowns.