I search on line for the road name I want, then cut paste the stock number and email my local brick and mortar guy: Ray at Trains on Tracks in Amherst, NH. There's no sales tax here so that's never an issue. Service is friendly and efficient. Since his orders come in a shipment direct to his store, there's no shipping if I run and pick it up. He has been the intermediary more than once on shipping stuff back to Lionel for warrantee work, so I have never had to do it.
Ray got me a SD70MAC (MTH) last week for 14 bucks more than Muffins, but again, no shipping.....worth the one hour drive to his store. If you are fortunate enough to have anyone local, give them a try. I always strive to support locals!