L-Fine via Amazon offers its L-Fine 2-Piece License Plate Frame in Black for $11.99. Coupon code "DENV8VP5" drops it to $8.99. Plus, Prime members bag free shipping. That's $21 off list and tied with our May mention as the lowest price we could find from a US-based seller. It includes screws and mounting hardware.
Note: Mentag via eBay offers a similar frame for $7.90 with free shipping. It ships from China and may take three to six weeks to arrive.