There's a couple of things you can do:

1) You can go to the Verizon store (as you suggested) but it will be expensive.

2) You could go on Ebay and buy a Verizon phone. This is significantly cheaper than the Verizon store but you have to call Verizon and make sure the electronic serial number (ESN) doesn't come up as stolen <--- Do this BEFORE you buy!

3) You could check around and see if any of your friends has upgraded their phones recently and have an old one you could use. This is by far the cheapest route, but you've got to find (and be willing to use) somebody's used phone.

Either way, if you end up with a used phone all you have to do is take it into the Verizon store and they'll activate it for you without a problem.