Lots of disenchanting required
There are quite a few tailoring made items in the game that disenchant into Illusion Dust, and there are 3 choices that have the best results. Keep in mind that guild perks and goblins have discounts on items such as Rune Thread. These aren't included in this article. The disenchant results are with the Bountiful Bags guild perk, however.
Illusion Dust is one of the more expensive
2 x Rune Thread
This is the most famous of the craftables. One headband requires 24 x Runecloth. Rune Threads are obtained from a vendor and cost 50 silver each.
Runecloth Pants are almost the same, but require 4 Runecloth and 1 Rune Thread less. In exchange, you need 2 Ironweb Spider Silk. Depending on the price of it, this item may be even more profitable to make. However, these provide a little bit less enchant mats. Still, the profit is there.
- 2 x Blue Dye
This is almost identical with the Runecloth Headband. Instead of requiring 24 runecloth and 1 gold worth of Rune Threads, you need only to spend 50 silver on the Rune Thread and 40 copper on the Blue Dyes. The disenchant results aren't noticeable from my experience, so you'll save roughly 50 silver from each.