its a simple, albeit heavy duty, home build. search here and the home shop machinists bbs you'll see some nice write ups on home builds. here's a simple hydraulic press - you can make them manual or motorized.
http://www.eagleequip.com/Merchant2/...SU5220_325.jpg
challenge for making one of big tonnage is finding a big enough dia cylinder at a reasonable cost, ie 5-6". I don't know how many tons you need, depends on length etc, machinery's handbook probably will tell you, but you'd want to overbuild it imo.
here's what i think of as a press brake
http://www.e-ci.com/products/brakes_maxform.html
the hydraulic is slower and usually you don't see them much bigger than 40 or 50 tons. the brake usually is bigger, heavier, faster, higher tonnage etc, but both more or less serve the same function. To make bend with a hydraulic press you create a die which are usually home made, there's not much to it.
in a production shop this would be done with a cnc punch or maybe laser then a press brake. I'd check out the cost of outsourcing those functions if you are doing volume. having seen those types of machines in action, it might be cheaper to have a production fab shop do the work and your core business is product development, distribution, marketing, etc. depends on volume i guess, but there's no manufacturing intellectual property in the above part, the value is in the sales/marketing side.