River buoy

We live on the Gasconade River in Missouri. In front of our property,
the river is usually about 2'-3' deep. At times, it gets as low as 8"
or so. We'd like to find some cheap buoys to mark a "safe channel"
that boaters should take to avoid rocks and grass and such that become
a problem when the water is shallow. We thought about just using milk
jugs, but don't want to make the river look trashy. We'd like to find
a cheap floating buoy that we can mark a channel in the river with.
Any suggestions, or sites to check out?

Question 2: Do you think this would be appreciated, or would others
view it as "trashing up the river" and rip the buoys out/steal them?