[Yorkie]

Check for oil leaks around the base of the cylinders or a farting sound when under load. Just like SCs they break the studs, especially the earlier one (I have a motor underneath my bench with a broken stud) and its a pain to fix but you can get a set of APE studs for $100. Clutch baskets wear due to chatter.

Take a very close look at the upper frame tubes that butt up to the headstock as they crack.

As for the price, worn ones here in SoCal (where the supply is quite good) tend to go for $2-3K and super clean ones, especially SLs and FEs hit $6K in mint condition. A typical mid year 900ss would be around $4K so the price looks in line. Not that I'm an expert but I can see these starting to rise in value as time goes by, especially for the 35+ crowd.

I'm not selling mine anytime soon.