Where are you moving in Mexico? The weather will dictate what you need to bring for clothing. I brought two pairs of shoes with toes over four years ago. My feet changed shape from wearing huaraches, so they don't fit anymore. I only own sandals now. If you are moving to a warm clime, you might want to bring a warmer outfit for visiting the mountains and a couple of sweaters or sweat shirts for the "cold" months. If you are moving to a city you should bring some more formal wear, up to and maybe including a suit and tie or distaff equivalent. Of course, you can buy all of this here as well, but if you already have it, just keep it within reason for the climate where you will spend most of your time.
You probably want to bring a good laptop computer with WiFi. That way you won't have to sweat getting an English-language keyboard and English OS here (which can be done).
If you are moving anywhere except the north shore of Lake Chapala, consider bringing a large hunk or more of a top-notch Vermont cheddar cheese. I'm dying just thinking about it. Super Lake's best cheddar is good, but it is from Oregon and not Vermont. No comparison.
Bring 100% cotton pillow protectors with plastic zippers. You can't find them here. Also bring sets of sheets, which you can find but at a premium over BB&B and usually with a lower thread count.
Bring Oxo utensils for non-stick pans, especially long handled tongs. You can't find the plastic-ended tongs in Mexico as far as we know, and we have looked high and low.
Bring a good quality salad spinner. We bought a stainless steel Oxo for $50 USD and we love it. Hard to find good quality here, if you can find at all.
Cook books and measuring cups come in handy. You can find liquid measuring cups in both ml and oz's but non-liquid measuring cups for, for example, flour, are only available (in our experience) for the metric system.
Lastly, anything that you can't live without from Trader Joe's.
¡Qué le vaya bien!