I recently purchased the budget Android phone, the Kyocera Risa, by Virgin Mobile and was looking for the best way to Root my device.
I did find an excellent guide to doing this:
How To Root Kyocera Rise v4.0.4 No PC Required
Although the Rise is a bit limited by it's internal hardware, I found that rooting this phone did improve performance as well as opening up various flexible options to other software apps, that would not have been possible otherwise.
The Rise does not support Custom ROMS, unfortunately, but there is some level of customization with apps such as ROM Toolbox, Pimp My Rom and Nova Launcher.