As with anyone in the world, I'd always accept free but legit zip code or postal code lists, but I'm realistic and willing to pay for a reputable source.  I need to track down a zip code list for Mexico but if I can get all of North America from one source it would be great too.  Latitude and Longitude are great helps as we are looking at distances and timezones would help with UTC offsetting.

I've been looking, emailing, and almost scammed by a few sources. So was curious from users who look at data if anyone has found a good source.