Roll Chart Holder
TPI Motorcycle Parts
Dual Star (Phone Orders only)
Princetontec Aqua Strobe (this has been the strobe I have used for a long time and is the choice of many Adventure Racers)
I modified a standard trail vinyl holder to attach onto the handlebars of my bike using a sewing machine. Some folks use bar-bags, rolls, or tank bags, which all cost no less than $40.
If you need an excuse to go buy one, check out Wolfman Luggage, Dual-Star and Motorcycle-Superstore.
An economic solution would be to buy some double-sided adhesive Velcro to attach a Vinyl Map Holder to your tank...then use Goo-Gone to remove the gunk.
No matter what you do, it is highly recommended that you have the appropriate maps at view's ready.
Anyhow, here's another possibilty:
REI Bar mounted Map Holder
Good Prices, too!