OXA Fashion via Amazon offers four Oxa Packing Cubes in Red for $19.99. Coupon code "3F6EVRY9" cuts it to $12.99. With free shipping, that's $7 off list and the lowest price we could find. It includes a laundry bag and a shoe bag.

Note: They're also available in blue or green for $14.94 with free shipping via the same coupon code as above.