RAL5010 is the best match I found. It is nearly the same color as Krylon True Blue and paint and powercoat shops can match it. All the blue on my 500 is 5010 powder.
My frame was powdercoated with RAL5017 the first time around. I hated it. I was re-done in 5010 and looks great.
Take a look through my build pics.
http://goo.gl/IZBRXZ