The Art Versus Money Dilemma

I know I said I was done writing under contract. My agent's excited about my 2008-2009 goals to hone the craft and write a better story than I've ever written before -- I fear she's dreaming about an auction that makes headlines at Publisher's Weekly. In truth, though, we're both hoping I create a story that readers will check out of the library again and again, and the thought of climbing fresh literary heights is invigorating.

But now I've been asked to write a children's book by a start-up on-line company. They need a story that's a tie-in for merchandise they'll be selling, so they have definite plot parameters along with a deadline. The catch is that they've offered me a fairly sweet financial deal.

Suddenly, I've tumbled from the lofty peaks of art to the desert reality of money -- the two sides of my full-time vocation. What to do? Here's the strange self-talk running through my brain:
  • You're not in your twenties, girlfriend; when it comes to time left for storytelling the hourglass is upside down. 
  • If you pass on opportunities like this to free up time for "real art," do you even have what it takes to create a so-called "great story?" And what about your literary reputation?
  • Chill out, snob, who's to say a merchandise-related story can't be defined as "great?" Heck, it could give joy to kids who read it -- why is that a lesser achievement than a starred review in the Horn Book?
  • It's only 6000 words or so; you could probably write it in a couple of months starting in the fall after revising Bamboo People this summer.
  • But a story, any story, takes creative energy. Is that a renewable resource?
Any advice?