I actually looked up the solomon island leaf frogs out of curousity - They are quite the eye catcher - I can see why you want one!

Unfortunatly from what I read they are regularly imported but do poorly. Also captive breeding of these cute little critters is not common.http://saurian.net/htm05/frog_solomon_leaffrog.html

Also I ran into a site that says they have solomon leaf frogs available but If i were you I would personally call them up because there website isn't so clear.
http://www.swaneesexotics.com/home/

Good luck and keep us posted!