This guy knows where the dollar store is obviously, Go to the Bike store ,
and have them order a "Two Fish" brand rubber block with 2 velcro straps at 90 degrees rifgt angle..

Then You can use a mini mag light or one of the LED flashlights of similar size,
and just tighten the strap onto the handlebar of whatever bike you mount..

I take it the OP has not had to run a small business and make payroll if the worry about getting ripped off
by paying 2 dollars rather than one ..

Look at the 2 Wars & the Arms Trade if you want to get exited about overpricing.. it's your Tax money, Buddy..