I have used these, Easy-Cut Strip Brush, 1/4" Wide x 3/16" High Backing, 3" Overall Height - https://www.mcmaster.com/#conveyor-brushes/=15r3gm6
$4.39 per foot.
One consideration is the stiffness. If mounted true vertical, any dust screen will add Z axis resistance. Softer or more pliable the better. When I put the short 1" easy-cut conveyor brushes on mine the added resistance really was significant. Since then I angle them out about 10 degrees. I bought 3 feet of 1", 2" and 3" to evaluate and am now just using the 3".
In the near future, in my next order from McMaster Carr, I will probably try the soft horsehair brushes - Galvanized Steel-Backed Conveyor Strip Brush, Horsehair Bristles, 3/16" Wide x 7/32" High Back, 3" Overall Height - https://www.mcmaster.com/#conveyor-brushes/=15r3k0q
Of course they are more than double the cost at $9.58 per foot, but dust foot doesn't take much.
Neither of these lets you see the cutting going on.