Groupon offers a coupon valid for a 16" x 20" Gallery-Wrapped Canvas from Canvas on Demand for $29.99. Coupon code "SALE" cuts it to $23.99. With free shipping. That's $6 under our mention from a month ago and the best deal we've seen. The credits expire 30 days after purchase. Deal ends November 13.
Of note, you can also buy two canvases for $39.99 with free shipping ($20 per print) via the above code.