A free 10 day trial is available, however after that a subscription costs $25/month or $250 for a full year. Lynda covers a lot more than just Adobe Illustrator - they have 3000 courses
Pro High quality content
Lynda works with professionals from industry, so you can be sure that the presenters actually know what they're talking about. All of the videos have quality visuals and audio, as well as a transcript tab just in case you missed something. Some courses include templates and worksheets to further drive home the point.