I have a pair from RunningSkirts.com I believe they come in purple. I like them very much but they are the only pair I have so I don't know how they compare to other brands of compression socks.
I have them in pink and they're great - do what they should and don't slip! Not quite as "compression-y" as some of the more technical socks/tights, though.
We (my sisters, neice and I) bought purple Sparkle Skirts at the Tinkerbell Expo. My sister chose the color because it's the kneck ribbon color for the Princess this year.
So I'm looking for other purple things to wear.
I thought purple compression socks would be good.
I also have a call into Runningskirts to see if they have purple princess tank tops. I don't see them on their web site. I wore the pink one for the Princess 1/2 last year.