Val Webb, a friend and fellow artist/teacher offers some very nice workshops online.  I have been taking them myself =)  You never stop learning!  They are nicely presented, well thought out, reasonably priced and fun :) http://valwebb.wordpress.com/2012/10/03/new-online-course-draw-paint-six-culinary-herbs/#comment-2823

Her current workshop is Drawing and Painting 6 Culinary Herbs.