Ah-ha! Thank you. I was eyeing them on the Scraprack website and had received a few emails about them, but hadn't realized they were in stores yet.
Here's some of the other new options, with discounted pricing for awhile:
NEW SCRAPRACK PRODUCTS
They're supposed to fit in the 14" cubes (Recollections, Jetmax, Kallax, Expedit). I just got a different storage cart, so I don't know that I need this solution anymore, but it seems really handy.