"There appears to be no motive."

Ok, and would gun-runners be happier if there was war or peace. I'll bet sales would be better if there were a war. What do we need for a war besides guns? Armies!

If they were paid in advance, what motive would they have to actually create the army? When the buyer returns and threatens them to give him his money back they would have the perfect line, "You and what army?" Seriously, let's say it was 50% down and 50% upon completion. If it were anything like real defense contracts SifoDyas probably would never have gotten off the planet due to the paperwork.

I don't think they'd have such an easy time unloading their stock either. How many other buyers are there with enough money to buy an army that is big enough to defeat the combined droid armies of virtually every commercial organization in the galaxy?
The line I always like is when she tells Obi Wan the Prime Minister is anxious to meet him and that they were worried he wasn't coming. It makes me imagine what the Kaminoans would have done if all these armies began reaching maturity every few months or years and there was no one to take them. Sure they're docile and take orders but what about when the food starts running out?

I want to say that I understand that the Kaminoans are not in any way a bigger part of the saga than just simple cloners filling an order. Just so that we're all on the same page, I don't believe there is some secret backstory or hidden plot. What I am agreeing with the orginal poster on, is that this "non-involvement" of the Kaminoans is never effectively communicated in the films and is counterintuitive. The point this thread is trying to make (IMO) is not that if you go back over the film with a fine toothed comb you can find something that is questionable or doesn't perfectly make sense, it is that if you try and simply follow the film you are left hanging at this point in the film. Basically, you have the following;
1) assassination attempt on Senator trying to stop creation of army for Republic
2) weapon used by assassin from strange planet
3) go to strange planet
4) strange planet making army for Republic and assassin is here
5) hmm, no motive here, let's bring the assassin in for questioning and see if he knows anyone who has motive...
Huh?