I agree with regards to Wall-E, CG isn't cheap, but TMNT cost roughly 30 million dollars. I know TMNT was done by Imagi (a Korean company) and this helped cut costs, but it's still ridiculous that Wall-E (which admittedly is technically superior) cost 6 times more to create.
As far as that Stargate Continuum remark goes about the cost of stepping it through the gate... someone's definitely doing something very wrong. The Stargate ripple effect is one of the easiest effects create in all CG-dom. I'm not exaggerating that a layman with no prior knowledge of 3D studio Max could most likely create something similar with only two hours of tutoring. $50,000 for that!? Yikes!
To my eyes, Wall-E looked a lot more detailed, though. Probably took a lot more man hours to do, and as you say, TMNT was done in Korea.
Well to be fair, they didn't say 50k to show the stargate, they said to step through it, which I'd guess would be a little more complex than just showing it?