The standard practice is to rate a press brake on max thickness of a full length piece of stock. That doesn't mean you can't bend heavier stock in shorter lengths.
All you need for bending 1/4" plate is a die with a 2" V opening. No danger of a standard die shattering and they certainly don't sell for thousands of bucks per foot.
If the legs are close, or fairly deep, you'd need a gooseneck punch. They're available in various sizes, and its fairly easy to look at the cross section drawings of the various ones available and decide what sort of leg length and spacing each one is good for.
On a brake like this one, you'd want to pay attention to the required tongue thickness on the dies. Stay away from anything that requires non-standard tooling or otherwise limits you to the tooling available from the brake manufacturer. You'd also need to look at the max vertical spacing between the ram and bed to make sure any punch and die combination you'd want to use will fit in the available space.
Power Brake Dies is one large 3rd party manufacturer of press brake tooling.
PRESS BRAKE TOOLING - PRESS BRAKE DIES | POWER BRAKE DIES They would have most anything you'd need and their website shows pretty good dimensioned cross sections of the various punches and dies. Punches and dies are commodity items for press brakes, so most manufacturers have about the same selection in the commonly used ones.
