It's a no-brainer. If the reason why accessory retrieval costs so much is to prevent devaluing of rare accessories by making them transient, let us retrieve them for personal use at no cost.
Of course, the accessory unbinding ticket would still be available for purchase. I just wanna take an accessory from an old costume and put it on a new, better one. Where's the harm in that?
Alternatively have the retrieval fee be something significantly less, something like 1% of the regular ticket value. You'd be paying 100 energy for an aura retrieval.
That might come at the cost of making bound accessories bind items you put them on to you, else a friend could take an aura off their tabard, put it on a hallow cloak, and then give you the hallow cloak when you'd then unbind the aura from.
Actually now that I say it like that I think I just found the reason why we can't do this...