it is pretty pricey, and most of the time the torque converter only goes bad when your tranny dumps.
The part alone can go up to 300 I think, and labor to drop the tranny and install will be at least 200 bucks, heck they charged me that to change a shock.
if you have any car competent buddies, with the right tools on a F body with a 700r4 tranny it isnt that tough, just takes time and you need a decent jack to support the tranny cause those things are heavy as anything