I bought a set of these cheap 200 W/S strobes off of that auction site to dip my to into the water of studio strobes without spending lots of cash. One of the three was dead on arrival. I disassembled and repaired it (had a cracked circuit board trace).
I was disappointed to discover (when I had it open) that the power rating was only about 120 to 150 W/S (not the 200 advertised. Based on the size of the Caps and the charge voltage) (disclaimer - this can be very dangerous if you don't know what you're doing), but even more disappointing was the fact that the light output was controlled by varying the voltage and NOT the firing time of the strobe. While this method does vary the light output (somewhat), it changes the color temperature too.
Ah well, you live and learn. It still helps me learn studio strobe techniques, so not all was lost.