Heck, selling for more than 2500 would make them worth the invintory slot.
Edit: Let me extend on this. While the gold up would be nice, I'd much rather prefer myself just having learned plans for you not droppping all together.
If we're not supposed to sell/trade them then drop rates only are there to gate acquisition.
But, frankly, it would be better just to gate crafting through the materials and lessen the emphasis on getting drops by making it such that you cannot drop a pattern that you already know (so that you're always on a path to something new). The drop rates don't have to be super-high so that there's still a sense of "I hope I get the one I want" but it would be a major step forward from what we currently have IMO.