Does it cost money to change your carrier on iPhones?

I use a really slow carrier and wanted to change it to a faster one, does this cost money?

Yes. You need to get it unlocked, ask at any phone shop and they should be able to do it. That or youtube it, there's probaby a tutorial that might be free? It cost me £10 but that was at a random phone booth so maybe a proper shop would be more expensive.

Well yea. You'd have to cancel with your current one & then get the phone unlocked in order to work with the new one.

The phone doesn't matter, it just depends what deals your carrier offers.