I recently picked up the body from the Skaven Hell Pit Abomination on Ebay for $10, combined with some left over Deamon Prince bits, and Lord of the Rings Ogre bits, was able to construct the start of my Great Unclean One / Ku'Gath. It is still a very early work in progress, with a lot of work to do on the head, and various greenstuff goodies throughout the body .
Left over Daemon Prince wing and a dremmel tool
Added in a sickle to add to the Nurgle aspect.
Side view of the head shows how much work is left to do...
Good view of the back shows the shoulder muscles and underbelly
Underbelly in greenstuff
updates to come....