As a novice pen turner and someone who is still gradually acclimating himself to using a metal lathe, I wanted to say that if you haven't used a metal lathe before, it's probably a good idea to purchase new rather than used.
I spent a while looking at used lathes in my locality (Sydney, Australia) and noticed a wide variety of problems that I figured would be especially difficult to remedy for someone with limited knowledge of metal lathes (i.e. myself!): extensive corrosion, extreme wear on ways, etc.
I figured that after factoring repairs and endless amounts of frustration, I'd be much better off purchasing a new 7x lathe. Now that's not to say that a new 7x lathe won't have its own share of issues. Invariably they're Chinese-made, so the fit and finish won't be the best and you'll have to make a few adjustments here and there to bring it up to a condition that will grant you the least amount of issues. But the adjustments are much more within the skill and knowledge of a new user.