I'd rather not pay full boat if I don't have to.
So tell me what you think of this:
(methods that have been confirmed to work after 8/24/14 (found further down the page (in link below)))
Instructions
Purchase your phone through
Bestbuy.com and choose the option to ship the phone to your home. Do not purchase in-store, activate in-store, or choose in-store pickup. While adding the phone to your cart it'll ask you to provide your Verizon login credentials; do so but choose the option "Keep existing plan". When you choose add to cart you'll see "There's a change from Verizon Wireless for unlimited data plans. Verizon Wireless has ended this plan option, so when you upgrade you'll be switched to their most common 2GB plan by default." but we've all ignored it. Once your phone arrives at your home, DO NOT TURN IT ON!!!!! Pull the SIM card out of the back of the phone and chop it up. For some phones, the SIM will come in a small box that you can toss out. Turning your phone on with the new SIM card or calling Verizon to activate the new SIM card WILL remove your unlimited data plan.
Take your SIM card from your old phone and place it into your new phone. Your SIM is already activated so there's nothing more you need to do. Your phone should be good to go and your Verizon contract will be renewed for 2 years but your unlimited data will stay intact. As required, your contract is renewed and as specified on Bestbuy's website you said you wanted to keep your unlimited data so you're not breaking your terms of service or doing anything unethical.
All SIM cards are not created equal. There are 3 common types of SIM cards; Mini SIM, Micro SIM, and Nano SIM. The Mini SIM is in some older phones. I can tell you for certain that the Samsung Galaxy S3, S4, and S5 all use the micro SIM card. Some iPhones use Nano SIM cards. The HTC Thunderbird uses a mini SIM card. However, they are all basically the same SIM but different sizes. This means you can cut your SIM to a smaller shape if need be or you can buy an adapter to make it bigger. If you're nervous about cutting your SIM, you can buy a special cutting tool to do it for you. I started a wiki for adding each phone and the SIM card size it uses.
FOUND HERE (many more details as well):
Upgrade and keep your Unlimited Data with Verizon 05-29-2014 - Slickdeals.net