Hi Javier & welcome to MR.
Your English looked fine to me. And there are heaps of members who are like you not native English speakers.
Have you considered buying a reader in the US and having it shipped to Argentina? I did that, using a mail forwarding company. Was heaps cheaper than buying one in Australia.
If you haven't decided on a reader yet, check out the
Wiki matrix and
this forum. It might help you narrowing it down.
And good luck on the saving - they are rather expensive. But then again, you will save money in future when you start buying eBooks.