I took NetJohn's helpful advice in Rickie B's forum entitled "Collecting Goals in 2010". When I described my set, I explained how I was building this set with the commons first. NetJohn advised me how the key dates increase in value the fastest. I took his advice and just purchased a 1915 P. My set, so far is perfectly matched. I am now 8 coins through. Next I'm buying the 1914 than the 1913. I think I did great for $80.00 shipped.