If you're ok with the aesthetic, you could go for 4th/5th edition Wardancers for torsos instead. They all have their arms spread out wildly, so conversion from swords to shuriken pistols etc should be really straightforward.
Also; they're still to be had really cheap too. I've been assembling my 'army that got away', 4th ed Wood Elves, for the past few months, and aside from the plastic archers, what pops up the most and cheapest are the Wardancers. If you take your time, you can easily bag 10 of them for €30,- still.
And how about 3rd ed 40K plastic Dark Eldar legs? Several of the poses would be perfect for a rider and others can easily be reposed. Also; cutting away the overtly pointy bits should make them suitable for Exodites. And lots of Dark Eldar bits can still be found aplenty too. Often badly painted, but as you'll only need the legs, you can afford to not be picky...