I also have a folder for GDS with folders for the designers and in that folder the scrapkits.
But a little addition: when I purchase a kit, before I click: "to my cart" I copy the link and paste it in a notepad. Also I copy the "product-name" and put that in the same notepad. I save the notepad in the same folder as the scrapkit with the name of the scrapkit + info.
Then, when I use a kit for a challenge, I can easily provide the credits: "product-name" goes in the "Keywords"area and the link to the product in the store-credits
BTW, did you know you can drag photos right from the folders in your explorer into a workspace in photoshop? (don't know if it works for PSE, but I guess so)
Just open the folder you want to work with, choose the photo(s) and drag them into your LO.