I very recently faced this dilema....
when buying a ct9 its very much a thrust issue, and I have been stung twice before (after buying privately-not through paypal or any starlet site)
So this time for €70 I was going to rebuild it myself using the most expensive kit from e-bay to be sure it was functioning as it should when finished.
As it turns out the turbo was still smoking as bad as it was before it was rebuilt. The condition of the shaft wheel and internals had been the best out of a bad lot which is why that turbo had been chosen.
There is now a turbo en route from Scotland and bought from a member on here. So after my experience`s perhaps buying a used but fully functional turbo from a member is best.