What ascenders to buy?

I only have one ascender, which was sort of bought for me on accident, but i would still like to climb trees and use my ascender, but I sure as hell dont want to shell out 50 bucks for another one.So can you ascend with one ascender? and if so, how would a person go about doing this? By the way, I have a petzl right hand ascender, blue.

You can use an ascdnder with a prusik loop. I would use the ascender on top, with the prusik loop on the bottom. Make sure you practice low. Also make sure you know how to descend safely. Switching to a descending system gets a lot of people in trouble.