The price difference is sometimes due to the name, but more than not it is the quality of materials and construction. Which is best for you will depend on what you want it for - looks or bouncing off rocks.
For example, I spent $700 for an ARB bumper, not that I do a lot of off-roading, but because we are getting over run by deer and I'm not gonna dodge them any more. Plus, I needed a new bumper and I like the looks of the ARB.

If you're on a budget and need functional guards, you could try looking in the scrap yards. Take some measurements with you - you might find something on a Ford, Chevy or Jeep that will come close enough to work.