With orders of $25 or more, Amazon offers the Chemical Guys Medium-Duty Carpet Brush with Drill Attachment in Yellow for $6.30 with free shipping. That's tied with our mention from three weeks ago as the lowest price we've seen. (It's the best deal now by $12.) This polypropylene brush features a 5" diameter.

Note: This item is sold as part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more