If you don't manage to get in before the ride sells out (or, if you plan on deciding at the last minute a la SadieKate ) the SLOBC sets up a website from which you can easily buy and sell Wildflower registrations.

I was able to sell my registration on that site with no hassle at all when it became apparent that I couldn't ride on account of the Head Cold from Hell which turned out to be a blessing in disguise.

I wish other ride organizers could do this, it's so convenient.