Not necessarily. A direct delivery service can be implemented alongside the centralized search you suggest, leaving the "walking to retainer" for those people that enjoy windows shopping and want to preview an item prior to implementation.
I would also addthe possibility to click on a item in the bazar (as a customer) and have that item displayed on the retainer instead of the one he's currently wearing, in order to improve the "preview" function when multiple items of the same type are for sale.
Other than that, I agree with most you said. I have been arguing most of it myself for a while.