Putting a Price on Your Work

How do you put a price on your paintings?  Most artists put their heart and soul into their work.  How do you price your heart and soul?  People have asked me which is my favorite painting.  I feel like they are my children; I labored and birthed them.  So how can I pick a favorite child?  How can I sell one of my children?  And what price would I put on it if I did?  Some say to add up the hours you took painting it plus supplies and give yourself an hourly wage.  That's a great idea if it were a 9 to 5 job and not 50% inspiration and 50% perspiration.  What is my time worth? $10 per hour? $20 per hour?  $25? $30?  I like to think like James MacNeill Whistler said in the courtroom testifying about why he priced his paintings so high.  He said he wasn't charging the public $200 for 2 hours work but $200 for a lifetime of experience in art.  Isn't that what it's all about?  Not the time I spent making it but the experience of all the others before that lead up to this one.  That's what my painting is worth.  A lifetime of experience in art.