Depending on how rough you plan to be with your equipment when traveling, you may not need something as bulletproof (and costly) as a Pelican case.

I modified a regular old American Tourister luggage bag by adding extra padding all around and a reinforcement panel in the bottom. I use some felt between the monolights that would actually be touching to prevent them from scratching each other and another piece of foam (wrapped in duct tape) to take up some space and provide a little more padding. The case holds 4 White Lightning monolights in the main compartment and gaffer's tape, power cords, and a power strip in the outer pocket. I've been carrying it around for about 2 years now:



I also have another monolight packed into a Marine drybox that I use if I'm only going to need one monolight. It has a storage compartment that fits in the top where I keep a power cord and some bungees. I use shop towels folded and wrapped in duct tape to serve as padding in the case: