I have made the deal and should be receiving the watch sometime next week. Considering that the 101.027 isn’t something that common, I think I fared well in the deal. My seller was kind enough to include a Lange box (pictured below—-any information about it would be appreciated from the experts here) that is not original to the watch, but most certainly a welcome addition. The certificate will follow via mail after the process is completed. 
Here is a photo of the watch
I’m quite excited. Thank you for all your helpful replies, it certainly helped me evaluate before making the leap.