I am a previous owner from the late 70s/early 80s when I was a kid. I got a second hand mk 2 for christmas and loved it until some git stole it from outside my house.
I have always promised myself I would get another one, probably to restore from original if possible. I have seen a few with wildly differing prices so thought I would join up here to hopefully get some advice before I buy something, and then when i have bought one some more advice with the restoration.
Get to know the model you want really well by studying all the pictures you can find. I see a lot advertised as "original unrestored" typically with incorrect grips, brake levers, pedals, handlebars, tyres and repro parts.