Even granting that actors get skills to fast; Even granting that skilled craftsmanship doesn't take long enough; I still think that a 15% 'Best Possible' result is too high.
You have your attitude because you expect to be able to kit your dwarves with the best possible of everything. Personally, I think that you shouldn't be readily able to get the best possible everything for even 1 dwarf.
In my mind, I have excised the descriptors. Quality comes in 5 flavors, 1, 1.2, 1.4, 1.6, 1.8, and 2.0.... The best possible Bed:
(7000$ used)
is only twice as good as the the worst possible Bed:
(200$ new)
Just a brief search on the internet and I've got a price range of x35... That's a little bit bigger than x2.
Using the price mod. = quality mod fact is a bit of a strawman, I'll admit. Let's look at actual quality instead. Certainly a good bed and 3k mattress is more than twice the quality of the 600 bucks worth of IKEA crap, but that's not readily transferable into numbers. The best I can come up with is the myth of the swordsmith who would judge his blades by how many men they would cut through. I can only imagine that his scale wasn't '1 guy, and some variable part of the next'
Edit: Formating and grammar
And because it's just too cool NOT to include, I have an Artifact bed: