Should the bezel of a Speedmaster 145.022-68 have a DON bezel? And if not, how much would that affect the value?
It should. Value would be affected, but I can't tell you a number, depends on the condition of the watch and the matching/missing DON then. From a couple of hundreds to maybe a couple of thousands, though not proportional to buying a single DON. That will cost you more in relation.
Yes it should and I would say a significant amount at they run $1500 and on up, over 2000 for nicer ones.