One of Costco’s newest offerings, Kirkland Signature-brand golf clubs, has landed the Issaquah, Washington-based retailer in legal trouble. In a patent infringement lawsuit filed last month, Carlsbad, California-based golf equipment company TaylorMade alleged Costco’s sold-out $499.99 Kirkland Signature clubs are identical to its $1,399 P790 irons. Costco began selling Kirkland Signature clubs in December. According to the lawsuit, Costco’s manufacturers had a team that included a former TaylorMade engineer who had worked at the company during the development of P790, which launched in 2017. C…