My first purchase from Check Out My Cards involved some rainbow chasing. Now I have three Felix Hernandez cards from the Spectrum - base (purple), red and gold, thanks to this jersey card numbered 21/99. Turquoise (#/25) could still be a bit of trouble, but we'll see. I am persistent.
By the way, I'm collecting the rainbow for Felix, Ichiro, Griffey and Lincecum in this set. I have the base cards for all of them but still need plenty of parallels.