Buy now. Pay later. Ish.
Get GUD for a Promise via Kwedit. What's that? Yes, rhotacism aside, you can get a PDF of GUD just for a promise that you'll pay for it later (via mail, credit card, or at your local 7-11!).
To test the service out we're offering 2-issue PDF bundles of GUD for an even $5.
What's required? You must have a GUD account (which is free). And you must have a Kwedit account (also free).