Winston,
1) There are two style of 14 x 6; the "Bundt Cake" cast-alloy style and the pressed aluminum that take the full wheel cover and LOOK like pressed steel rims.
2) For the latter, in 14 x 6, they are quite rare, as JonnyB points out. However, go to the parts for sale forum here, and look up "Scoot"; he might have some for sale as he scoured the west coast for them.
3) Unless you are running grossly oversized tires, you can easily get by with the much less costly and far more readily available 5.5 x 14; remember, this was, initially, the rim size for the 230 SL. The standard tire sizes fit without issue.
What I've found is many people want the 6"; are aghast at the price; but ignore the fact that the 5.5s are nearly identical, do the same thing, and nobody will know--and they are available.
I have the 5.5 as my spare, and the 6" ones on the four corners--but I got them when they were only extremely hard to find, not near impossible. Today, I'd go with the 5.5s before they are all gone. The difference in unsprung weight is substantial.