The Commerce Claus: Mr and Mrs McAlaster

INSTRUCTIONS: Give a full answer. Consider the facts, including what is given and what can be presumed from the facts. Then apply the rules to the facts. Please follow the rubric and review the example before completing assignment.
Mr. and Mrs. Jacob McAlaster own a small variety store in central Wisconsin. It provides groceries, convenience items, and a limited selection of cards and gifts. They own just the one store and this is not a chain. The majority of their customers are central Wisconsin locals, but because the store is located on a main street, they do serve the occasional traveler from outside the area. The McAlasters' store does not comply with the Americans with Disabilities Act (ADA) (a federal statute) because the doors leading into and out of the premises are not wide enough to accomodate a wheel chair. Nor does the store have an access ramp--only four steps leading into the main entrance and a back entrance, which leads to a basement storage area. It would cost the McAlasters in excess of $50,000 to widen the entry door and add a ramp. The store complies with all state and local regulations, however, it does not, as indicated, comply with the ADA. The McAlasters do not believe the ADA applies to their establishment because it is just a little local store. Moreover, according to a family friend who reads legal fiction for a hobby, the store does not impact interstate commerce and therefore federal law does not apply.
Does the Commerce Clause from Article I give the federal government the authority to require the McAlaster's store to comply with the ADA, add a ramp and widen the doors, or be otherwise subject to fines and/or jail for failure to comply? Why or why not?
Could any other branch of the federal government (Executive or Judicial) use any of their powers to attempt to regulate the store?