Besides Barter sync, wishlist items would be better managed if they were to be removed automatically without intervention.
They *are* removed automatically when they show up in your Steam library. But first they're flagged as removed, and then when you visit your wishlist, the items are removed automatically, and you're given the opportunity to re-add them. You do visit your wishlist tab from time to time, right..?
I could do it on any page (with a bit more work), but I'd also risk showing it on a page that you're not paying attention to, e.g. a forum page or even the homepage, some may ignore it completely.