I made a mistake- the S-220 is also dealer only and has a Briggs engine.I highlighted the difference in our post. You can buy the same cheap stuff at the dealer that you can at the box store. Only difference is the price.
The 100 series is sold new at Big Box stores and, generally, not at dealers that I know of, but maybe some places. The 200 series, X300 series, X500 and X700 are sold at dealers and never at big box stores.