A lot of turners get a slow speed 8" grinder with the wolverine set up. Woodcraft sells a package that is a good deal, and not many people that have the set up have complaints. You will still need one of the vari-grind jigs, and the skew jig, if necessary. That entire setup will cost between $250-$300. I have the setup (sans the skew jig) and have been learning to use it.
I started with the PSI version and it is no where near as nice. I struggled for a long time. In the meantime, I invested in the Tormek, and later the wolverine/WC setup.
The Tormek is expensive, but can also sharpen many other tools. It generally takes longer (many argue different points here), but as long as you are sharpening (not shaping) it isn't bad. You will also not over heat the tool on the Tormek. I really like it, but have lately been trying to learn the wolverine for quick sharpening where a really fine edge is not needed; i.e. roughing.
I only use the Tormek for my skews. I use oval skews for final pen turning.
Oh, some complain about the wet sharpeners making a mess. In my experience, the few drops of water you get are no where the mess that flies everywhere from a dry grinder. Plus, you don't have to worry about breathing all of the silica and other nasties you get from dry grinding, with the wet sharpener.
I have also read that no matter which wet sharpener a person gets (Tormek, Jet, Grizzly), the jigs to invest in are the Tormek jigs. They are much better.
I hope this was clear as mud, or better.... Good luck.