You should easily be able to get nine-speed shifters. I believe they are still made, and any of the usual online sources such as Jenson.com or UniversalCycles.com will have them.

FWIW, I like the *idea* of 10-speed in a two-ring configuration. I'm planning to go that way on my next build. With three rings up front, I'd just as soon go nine-speed. When it comes down to it, I favor a two-ring setup regardless of the number of speeds in the back.