I don't know of anyone offering truly hand-knit hose like that, but if it's just custom-colored Argyle hose you're after, there are several people who offer them.

The Scottish Tartans Museum gift shop, as Matt has pointed out already.

Skye Highland Outfitters offers custom made hose too (machine knit). I had a pair made by them (and another in process), and I'm extremely happy with them. They won't have quite the same character as the hand-knit hose you showed, but you'll get the custom colors you're after. Here is my example: