Does anyone have any suggestions for mounting a planet bike superflash to a rear rack? I followed recommendations from here, put a "items wanted" ad on CL, and got a rear rack for $9 and a set of fenders for $10. But now, I have nowhere to mount my superflash. I know planet bike makes a mount specific for rear racks, but at $5 + $5 shipping, it costs as much as my fenders!

Does anyone have any cheap-o DIY solutions to this problem?

Thanks!