You didn't tell us anything about width of cuts and depth of bends you
want to make. That would make a difference.

I bought one of the Harbor Freight Beverly-like shears a few years ago
and am very happy with it. I shear up to 16 gage mild steel with it.
If you mark your work out well, you can do nice straight crisp cuts.
The neat thing about this style of shear is that you can do curves well,
too. It ought to do alumimum like butter. They are about $150.

For a cheap quick bending brake, make one from a piece of angle iron.
Example: You need to make approx 90° bends in a sheet that's 2 feet wide---
Take 6 feet of 2 1/2" X 2 1/2" X 1/4" angle iron. Cut out one leg of
the middle foot. Now make a "hairpin" shape, heating (with a torch) and
bending that center section into a loop. This give you the basic brake.

After getting the basic shape, I opened mine back up so I could bolt it
to a bench with countersunk bolts. Then I heated it back up and rebent
it to shape.

To use it. insert the part to be bent from the back side, apply C clamps
to either side of the work and pull down, using a soft faced hammer as
needed. You can see that this isn't going to make professional bends on
heavy stuff, but it may fit your needs.

If the idea sounds useful but the construction details don't make sense,
email me off list and I can take a picture and put it on my website.

If you are going to go with an undersized brake and "abuse" it, try to
get a C clamp with a deep enough throat that you can clamp at the middle
of the machines clamp bar.

Pete Stanaitis