My curiosity was piqued, so I checked it out and found this really helpful [archived] wiki on the LeanPub page (and a nice video by David): http://web.archive.org/web/20190407035722/https://wiki.info-...

And David, good call on the price. I wouldn't respect anyone who would begrudge you the price of your most hard-won knowledge, esp when it sounds like you do consulting.