It's been a bit but for others looking, I bought one of these for a DIY dust shoe I had on a router a few years ago. I got mine at a local big box home improvement store for about $10. They are door sweeps and usually come in various lengths and you can get different height/length brushes. I've seen both aluminum which bends to the shoe shape or rubber. Mine worked well.
Hager 806S Door Bottom Sweeps - Doorhardware Supply