One of the good things that Renderosity added in a recent site upgrade was the green 'Purchased' button when you go to an item page.

I would like to see the shopping pages that come before the item page also have the ability to show whether an item is purchased.

Have the shopping cart icon on that page be a different color, maybe yellow or blue.  Then a customer can see at a glance what they've purchased.

They can spend more time shopping for items they'd like and less time accidentally clicking on items they may already have, or, if you're like me, clicking on an item because you're pretty sure you already have it but want to see what the system thinks (Bogos through vendors don't show up, obviously. So not showing a 'purchased' button does not always mean you may not already own it.) It takes about 10-20 seconds or more for a page to load through the renderosity site, so every four or five clicks (and duplicate pages viewed) or so is a minute or more wasted on items that won't be bought.