Market Basket's website does not list lobster prices. However, the site provides a "Weekly Specials" advertisement circular. The circular includes a seafood section where the price of lobster could potentially be listed when on special.
From the Market Basket homepage, click on the "Weekly Specials" section of the website. A PDF version of the circular will then open in a new window. The specials are updated every Tuesday.
Market Basket's website also provides a full catering menu. The catering menu states that lobster tails are priced at market. Market pricing is based on the price the restaurant paid for their supply of lobster.