It now resides in my home in Kansas City and if I were to purchase one again, here's where I would start (since you can't Google, "really cool mid century magazine rack that someone painted bright green").
First, try the following search words: Library Media Rack, Children's Book Display, Library Magazine Rack, Mid Century Library Shelving.
Any combination of those words should yield you some results on Craigslist, Ebay and plain old Google.
Like any good hunt, it will require patience and diligence to track one down.
Magzineracks.com sells a similar version that is legless:
There are other library supply websites you can purchase things from, although we liked the looks of this one.
A piece of MDF could be fitted inside the bottom (they are typically hollow, although I have never purchased from this company before), nailed in and have mid century legs attached to them for a vintage look. Simply hit up a few auctions and you are sure to find a side table with such legs for a few bucks.
Don't forget to keep an eye out at auctions for schools across the country, you never know what you'll find. Also, be sure to use the search function on sites like auctionfinder.com to help narrow things down. Even if the auction is 12 states away, you might be able to find someone you know willing to make the trek for you!