My recommendation since it would be a local sale and no warranty is to take a couple of rolls of film and have the seller let you expose them with the two lenses at different settings. Develop or have the film developed to be sure it is functioning correctly and the light seal is in good condition. Be sure that the camera is not jamming especially when trying the extension tubes.
About 10-12 years ago I purchased a Hasselblad 350mm lens in excellent condition that was about 30 years old at that time. The seller had a 15 day return policy so I was able to test it that way. Fortunately it was perfect and I have been using trouble free since. It was a bargin costing 1/10th of what a new one.
I have an 80, 150, 250, 350, 2x, 8, 16,32, 56 ext tubes and the 50 FLE which I really like.
i can't help price wise but remember that KEH is in business to make a profit and would probably offer you 40 - 50% of what they would sell it for if it was you selling it to them.
http://www.jeffreyglasser.com/