CDMA devices are not "locked" or "unlocked" in the GSM sense. And with CDMA devices, it's not as simple as just going from one carrier to another like it is with GSM devices. Even though PagePlus uses Verizon's network, some changes will have to be made to the phone in order for it to work with their service. I've also read that PagePlus isn't letting Verizon LTE phones on their network.
If you want a Verizon device, the best place to get one is through Verizon or an authorized Verizon retailer. You can also look on eBay for people who bought one from Verizon and are selling it. Since Verizon devices are exactly that - Verizon devices - there aren't many places that sell the phones that are not connected to Verizon. It's not like unbranded international GSM phones that several stores and websites sell. Typically, carrier branded phones are only sold by the carrier and their affiliates. Short of buying from Verizon, you'll be looking at hefty prices on eBay and on other resale sites for a good while.
Honestly, if you have an Incredible, that means you have unlimited data, and that means you might be better off sticking with Verizon. For the time being, if you upgrade to a LTE device, you can keep your unlimited data plan. Unlimited data + LTE is a great thing.