How and where can I buy factory unlocked iPhones?

I want to buy it like without a carrier plan or anything and I don't want to buy it off ebay amazon. If I go to apple store can I buy it there without a carrier and go back or go a carrier store and have it activated there or just go to at&t or Verizon and buy at full price without plan. If I can do that at the apple store about how much will it cost it doesn't recall matter about iphone but 5-5c.

How to use my iPhone 5S (Verizon) in Mexico?

Anyone know how much a plan is from Verizon to add on international to your regular plan? Also, a co-worker mentioned to me it may be possible to unlock your phone and get a SIM card in Mexico. I'm looking for a RELIABLE option but one that is also affordable.

I'm traveling with one other person that has an iPhone 5S on AT&T so if you know how their phone can work please tell us as well.

What are some good quality/longer lasting earbuds that aren't too expensive?

I'm looking to spend $20-$30 on some earbuds from amazon.com that will last me a while. I always run into the problem of only one side of the earbuds working and it frustrates me lol. I like the part that goes into your ear to be soft and removable (hard to explain since I don't know what they're called), not hard like the standard earbuds you get with an Iphone or what not. I like it when they have bass but not too much that it drowns the rest of the music/vocals out. Any suggestions?