I fancy buying a classic bike up to £10k to have for tinkering and the attraction of no tax or MOT, needs to be non Ducati, reasonable riding position, done the Triumph/BSA/Norton things years ago, not 2 stroke fan, so what would you consider?
So pre 1980 then and a 4 stroke @ £10k or less Z1R, GS1000S Check the up coming Bonham's & Coy's auctions - something might just pop up that you wouldn't have considered...
I have had plenty over the years, many were 2 strokes and Kawasaki Triples, they are not cheap to buy or maintain so be warned. I also dipped an elbow into the Brit Iron market with a BSA Gold Flash 650 and a Velocette Venom 500 the latter of which, was beautiful but not easy to live with.... pause for puns. An appreciating classic is the route you should take... maybe a ZX9R or ZRX 1100/1200
A classic BMW,click your heels together and go marching to the bank with the sales bonus in ten years time
Oil cooled Gsxr750/1100 be quick though they are appreciating rapidly...Slabside 1985>87 ,Slingshot 1988>91.
I settled on a 1978 Honda CB750F1, considerably cheaper than an earlier K model. I’m sure it will appreciate in time.