Setting up a new account - should I buy a new phone myself or get one with the new account?

We are living outside the USA and are moving back soon. We will setup a new account.

I was thinking of buying an iPhone mini on eBay ~$500 and setting up the account with that new phone or would it be better/cheaper to get a phone from Verizon? I don’t really want to pad my monthly cost of the service with a phone payment as well so I thought I may end up saving money bringing a phone instead.

I’ll also include my wife and she has a newer phone already that will be put on the account.

Also is it even possible to setup the account while outside the country? (Port phone numbers etc) Wife said we should do that before traveling home as our phones may not work in the states at all with the foreign SIM cards.