i find that adding a checkbox for what's wishlisted is an excellent idea, to make it possible to see wishlisted items in a particular sale or category.. and since it's so simple to code, why not only the owned items too as asked by the OP.

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IN THE END, MERITOCRACY HAS NOT ONLY PERMEATED OUR DAILY LIVES AND WORK, BUT ALSO OUR HEARTS, OUR MINDS AND OUR PERCEPTION OF ART...