I find some great sites to check out for ko transformers are Toyhell and Kotoys. They show alot of the knockoffs. I actually enjoy the Knockoffs and have quite a few. Not really worth anything but really cool sometimes. My fav have been the KO Starsaber. Big and cool and the plastic isnt that bad. Ko's are great for kitbashing as well.
I have dealt with KOTOYS and Toy Hell and both times I had a good experience. Kotoys was really good and had good prices and shipping is cheap and quick and comes with tracking that actually works.