Notice that I said UPWARDS.
It depends on the model of stove you have on how much it's going to cost to replace the cat. I've seen replacement cat units go for as little as $75 and as much as $550. It all depends on the make, model, and age of the stove and whether you have to go through a dealer or not.
A cat vs. a reburner, when both have the same efficiency and output ratings and the same firebox size are going to use the same amount of wood. No magic in the numbers.
As for temperatures, I don't know what temps a reburner hits.
Here's an interesting, but damned hard to read, website that talks about cats and non cats. He's not a fan of the cats, but he's not trashing them, either. Just some good, solid, information on the differences between the two, and why he feels that reburner stoves are better.
http://chimneysweeponline.com/hocats.htm