As of 4/20/10 in Lunia, all RB skill dyes (+1 or +2) are available via cash shop (30 or 100 g coins respectively, quite expensive). The only skill dye you can not buy now are the ultimate skill dyes (only +1 available now from blue cyrstal apple).

As of 4/8/10, there are 2 RB skill dyes released in the cash shop, which you can buy either +1 or +2 version for 30g coins and 100g coins respectively. There are still no +2 skill dyes for the other 2 RB skills or Ultimate skill yet.

As of 3/25/10, with the release of Dark Eir, the remaining +2 skill dyes for the regular item slots have appeared. So currently, the only skills that do not have +2 are Ultimate, at level Lunia Gold 60, the one that fits in all places, not just in one specific spot, and the other rare spots (mask/back/lower/etc1).

As of 3/10/10, there's an update to the cash items again, this time giving you +2 skill dyes to the remaining main pieces (trousers/weapon/support), there's a total of 7 skill dyes for each character this time. Keep in mind, these +2 skills are not all of the available skills for the specific area, just like the previous update, there's more +1 skill dye variety than +2.