The starter on eBay used to $100 is now around $200. He uses an OEM Nippondenso starter motor if i'm not mistaken. Goes by the ebay ID name of hiperformanceusa but it appears he's not offering the 911 starter anymore.
I have one of the hiperformanceusa starters and its a pretty good unit. But comes with the thick shim if you happen to need it, which is hokey. I haven't put mine to a lot of use since I installed it when I last rebuilt the engine and the engine had an oiling failure soon thereafter. Just now getting the engine back together for next racing season.
The IMI starters that Pelican sells have been good but some people have had problems that may or may not be attributed to the starter not properly engaging the ring gear, so keep that in mind/do a search to help your decision. There's conflicting information whether or not a shim should be used with the IMI
http://forums.pelicanparts.com/porsche-911-technical-forum/682957-starter-ring-failure-twice-3-weeks-help.html
If you want a no-hassle top quality lightweight starter, you can't go wrong with a Tilton Super Starter. Tilton parts are supreme quality Made in USA.
Pre-89 Porsche 911/914/930 Standard Duty Super Starter