Samsung Galaxy S4
 

Does anyone here know how to unlock a Galaxy S4, so that I could use it with another company. Verizon is just too expensive.

Typically the phone is tied to a carrier so you might be SOL. Go to the company you want with your current phone and ask them.

I may be wrong, but I thought that recently there was some legislation to allow changing carriers, not sure. I would suggest just taking your phone to the carrier that you want and asking them to change it over.
Also, as a Verizon customer, tell them you are considering moving, you may be surprised at what they can do to keep you...

If you have completed your contract term (usually two years), call Verizon and ask them to unlock the phone. They'll send a code to unlock the phone. I unlock phones so that I can use them with other carriers overseas.

Basically, they charge you 1/24th of the cost of your phone every month, and if you cancel your contract early they charge you an "early termination fee" to recoup the cost of the phone. If you don't get a new phone ever two years, you're still paying that fee, even though you're not getting anything in return.