Thinking of Getting A New Phone

I'm thinking of getting a replacement cell phone. I have about 10 months left on my Verizon contract, and they will not let me upgrade till the contract is up. I asked.
Where is a good place to get a good used semi-smart phone or a refurbished phone? What are some things to look for when I do this?
I have a Samsung Intensity III slider phone now, not a smart phone. It shorts out and shuts off every time I slide the keyboard back into the phone.