Sounds like a reasonable price to me. I have 119k miles on mine and plan to at least double this mileage. The bottom ends of these engines are phenomenal, with silicon impregnated cylinder walls. On the other hand, I don't want to know how much a valve job would be ....
Be aware that repairs are more expensive on the 400E/500E compared to the 300E due to difficulty with access to many components. Not a deal breaker, in my opinion, but something to know about.