The streets here are full of 125's- Honda, Yamaha and tons of Chinese makes. Here's a link to see what Honda sells here
Sadly, because of import taxes and high prices they don't offer nearly the selection of bikes that they do in the US, and many Mexicans end up turning to the cheap (and poorly made) Chinese bikes. I often find myself on a major manufacturers website going "man that bike would be perfect for Mexico", but they don't sell them here. They only just introduced the KLR650 to Mexico a couple of years ago.
The ones you mentioned haven't been sold here in a few years, and are becoming scarcer. The ones you can find second hand have probably been ridden half to death as delivery bikes. A quick search on mercadolibre (Mexican ebay) didn't turn up any at all. I used to want one, but they are hard to find for sale.
I have a Yamaha XTZ125 that I use for city riding. I don't obsess over fuel economy but I fill it up about once every three weeks and ride it at least 5 days a week. I think thats pretty good. disclaimer- I'm about to try and sell it, but only because I want a Hypermotard.
If you can bring a bike from the US it'll be cheaper. Finding parts isn't usually a big deal, I order stuff from the US all the time, never had to pay any kind of customs duty or taxes or anything. For my BMW I find half the time I can get it cheaper from the US, half the time its the same or even sometimes cheaper from the dealer here.