As for buying a market model, some people here on this site will steer you away from the Donkee models due to excessive vibration. I don't have any experience with the Donkee models myself, since I'm using an older HyTek spinner. The Vertex model has seemed to get some favorable reviews on this site. If you set your "preferences" back for a couple of months, you will find quite a bit of older posts regarding some spinners here on Coverstock Preparation.
I will say that it is nice to have your own spinner. You can save quite a bit of money versus taking your ball to the Pro Shop, and in time the spinner can pay for itself. Plus, with easy access to change the coverstock texture, you can play around more to see if you find a texture that you like better.