I currently have Sprint and my contract is up however I'm not sure if I want to continue with Sprint or go with Verizon just yet. What I do want to do is get a new phone without extending my contract with Sprint for another 2years.

IS this possible?

You will have to wait until your contract is up and you decide because even though cell phone companies use the same phones like Samsung, Nokia and other brands they have different hardware or coding or something that makes them incompatible if you switch service.

My question was more of replacing my old phone with a new phone without extending my contract- is this possible? My contract with Sprint ended in October.

I would get a new phone once I've decided to either stay with Sprint or make the switch.

Yeah you can buy new phones anytime you want. Contracts are not needed to buy phones. The contracts are for the service only.