I've outsourced my ogryn-gathering to a non-GW producer (Westwind productions, if anyone is curious). Then again, the fluff for my army would have my orgyns be guys in mech suits instead of abhumans. Your results may vary. I would agree with most of these people that Fantasy Ogre Bulls are the way to go, though you may need to do some bits-gathering to make them appropriate for 40k.