I would say that the fact is 'saving' is singular and 'savings' is plural. This dictates the verb that follows. You could say A saving of $20 is ... or Savings of $20 are ...
A basement bathroom can be built for about $15,200, Fred estimates. Of that, plumbing is the largest component. These prices are based on costs for a small bath measuring about 6 by 8 feet, with 8-foot ceilings. However, many basements are limited to a 7-foot ceiling. Another potential cost-saving location for a new bathroom is the attic.
1 Adding new floor space to your home for a basic 6x8-foot bathroom addition starts around $25,000-$50,000 and goes up depending on complexity, quality of fixtures, number of amenities and local labor rates. Remodeling Magazine pegs the price of a 6x8-foot bathroom addition at averages of $33,188-$41,195 in the Midwest, $34,876-$42,491 along the East Coast and $35,987-$47,052 in the Western states. 2  For a spa-quality 100-square-foot master bath the survey says it averages $75,812 nationwide.