I recomend you to buy to companies directly. If something goes wrong with the any of the players (from the fabric, like fake space) you can demand the company to change it and, if it doesn't want to, you can sue it (depending of you local laws) of don't doing what it told you it was going to do (I mean, it don't give you what you demanded. Like 400 MP4 player of 2GB capacity, when they're really of 1GB).
Also, try (if you buy to companies) to have all transactions written and signed. I mean, you buy a dozen of player then ask for a note (don't remember, but it's the paper where says what you bought and what you paid).
At last, this can work perfectly in Mexico: you're straight (not illegal
).
Read-ya