Howdy! I live in Mexicali, Mexico, and go to the Walmart in Calexico, California about twice a month - I've seen the magazine there (and its counterpart, Geek Magazine) at the beginning of every month, but they run out pretty quickly since they're free and at the reach of anyone. The most copies I've seen, right at the start of the month, have been 20.
The only difference I've noticed between the print version and the online PDF / Reader version... is the ads. And maybe an extra ad insert, and sometimes it's inside a baggie.
At my store they usually put these in the middle of the electronics section, next to the computers, but they also used to be next to the video games. Sorry for the late reply.