Similar sort of thing with me Mike. I get great enjoyment fixing mechanical stuff but there's a lot of bargains (MOT failures) which have succumbed to tin worm and can be had for peanuts. I got deeply into doing this sort of thing for a while because sills, floors and box sections don't need any great panel beating skills. However some years ago I got fed up with red hot underseal dripping onto my chest and also began to worry about the high strength steels starting to be used in vehicles which a local body man told me require specialist welding techniques if they are not to become brittle due to crystalline changes in the metal as a result of using something like a "Hobby" MIG on them. That was when I started getting much more interested in my old horticultural machinery, that and because I can work on them in a nice warm workshop!I ran it for a while, it was at the age where they had a simple computer with a vacuum advance and no points etc. I was lucky to get a good s/h unit as they were unreliable. Still got a good price when sold.
Generally I would buy knowing they needed fixing mechanically, not rust though as I gave up on massive welding jobs years ago. Several of my Doblos in the past were in the £300 price range, runners but had some issue or other.
After retiring I got bored and still wanted to repair mechanical things so that is why some came along.
Until recently before driving issue after a fall I used to go to a mates and we would fix old Cyclemasters, Seagull outboards, 7 tonne Case digger hydraulics etc. followed up by a farm house breakfast, though now I have trouble swallowing certain foods so even that pleasure is gone.
