At $10 a month that's $120 a year...for about $60 one-time payment you can get a Freedom Keychain Bluetooth GPS puck that will link up with your BB and allow you to use any
GPS software you like (including VZNav) for no monthly charge.
It's really small, very fast and reliable, and you don't end up paying for it when you're not using it...in my case I found that after the initial "Oooo - I have GPS & voice nav!" excitement wore off that I only rarely actually needed to use it.
Check out the review of it here... Review: Freedom Input Keychain GPS 2000 Bluetooth Receiver
It's very cool...