To go a bit further than Led did.
My suppliers want to sell whole beams of the stuff, and while they are great prices, they may be more than you need.
But from my post Roger Groom says he has some, maybe he can sell and post you the smaller quantity you need.
Or contact the Cutty Sark trust and see if you can get some smaller offcuts. Too small to palatise but still worthwhile sections of teak at reasonable prices.