Here’s the latest info from DSP for ordering books for GRL:

If you plan to attend GRL in Chicago this October, you can preorder paperbacks on the DSP site between now and September 21 to be picked up at the event, and if you use the code GRL2014, you won’t have to pay shipping! Any orders using this code will only be available for pickup at GRL. You can order books from any author, even if the author isn’t attending GRL.

The code is valid on all in-stock paperbacks and good for multiple orders. DSP will have a special GRL preorder sale Sept. 17-21 where ALL paperbacks will be in-stock for preorders, so if something isn’t available now, you can check back then.