The average minimum cost per finished square foot of Wilsonart solid surface countertops is $38.75. The average maximum cost per finished square foot of Wilsonart solid surface countertops is $74.55.In addition to the cost of the solid surface sheets that become the countertop, homeowners will also need to pay for edging pieces. These cost an average of $14.50 per linear foot.rades. Wilsonart does not grade their solid surface countertops. However, the company does provide the product in two thicknesses, including .25 inch and .5 inch. Wilsonart also offers a wide range of color groups and product lines. These groupings include particulates and solid colors.