I have heard that T-Mobile tends to not work when you leave populated areas like cities. I don't know how much of a problem that is for you...

If the only problem is having an old phone, you can buy a newer model, Verizon-capable phone, but a cheaper one (although not an LG Shine, because the screens on those tend to break) that's not so fancy, use the rest of the money for groceries/emergencies/etc. and wait until a phone you want that Verizon carries comes out.

Just a suggestion :)