The Verizon version of the Samsung Galaxy S4 Developer Edition just became available on Samsung's website for $649.99. To be clear this is the 16GB SCH-I545 model and it is carrier unlocked and includes an unlocked bootloader. This price is the same for folks who want to simply get the Verizon (bloatware included) version of the device off contract, which probably makes little sense to choose.
This version of the phone isn't available on Verizon's website just yet, so this is an opportunity to get it a bit ahead of some folks. If you want to keep your grandfathered unlimited plan and get a Galaxy S4, then this is your best option. Here's a link to Samsung below.
Source: Samsung - Developer Edition of the Verizon Galaxy S4