I have the CQC-4KXL it's, well, okay. Minor lock rock, grind is a bit off, but totally usable. It was worth what I paid for it, but not much more. That said, the next cheapest alternative with a wave opener is probably a $70 waved Spyderco Endura, literally twice the price I paid. I have my issues with Ernie Emerson, but he's a great designer and one who's designs have simply never been available at that price.
Would I buy another one? No, not really worth it to me. The one I have will likely end up a gift, possibly after a trip to KAI to correct the lock rock. Do I regret buying it? Nah, it's an okay knife for the money, just not a spectacular one. If I start feeling like I need a cheap, waved knife again in the future I'll probably buy a Byrd and throw a zip tie on it.