Pacific Edge has the larger buoys in 2 different colors for about $6 each. I bought some last week to replace the little floats and plastic bottles with light sticks.
I added reflective tape plus light sticks on the large buoys (so that other boaters not using a spotlight can see your float also). Take a look at Mark's customized hoop net at his shop that he uses. You may want to do something similar for efficiency and to keep ropes from getting tangled in propellers.