Yesterday, Apple began offering refurbished models of the current 27-inch iMac in its online store for the first time, and while two of the three available models quickly sold out, the company is clearly working to expand availability by adding not only another 27-inch configuration but also a pair of 21.5-inch models today. The newly listed models, all of which ship in 1-5 business days, include: - 21.5-inch iMac 2.7GHz quad-core Intel Core i5 with 8 GB RAM, 1 TB hard drive, and Intel Iris Pro graphics: $1099 ($200 savings) -