I recently bought memory for my MacBook from Crucial even though some reviews said that some third party memory modules didn’t work well with the Aluminum MacBook, including Crucial, but my experience is completely different.
First I want to say that the memory was cheap compared to the prices I received from some Apple resellers and also from other shops that sell RAM. I got a 4GB kit for $65 dollars vs. $150 dollars for each 2GB module at the local shops so for me it was a great deal. I had to pay $20 dollars for shipping and a few more for taxes to UPS for importing it but I also bought memory for other computers so it was a reasonable price.
My advice for Mexican buyers is to pay with Paypal as the order is processed immediately and the product is ready to be shipped the same day. I ordered on Thursday and my package was in my door on Monday.
So far so good the memory has been working great and my MacBook feels faster and more responsive. I really recommend Crucial if you plan to buy memory and it doesn’t matter if it is a Mac or a PC.