I turned a regular sling-stud attached bipod into an arca rail bipod for my new rifles. I already had the bipod, and the arca attachment was $13.60 on amazon. With a 1/4-20 bolt and a washer, you can make one too.
Update - you may want to turn the arca adapter so the adjustment can be made with the left hand. You can keep your dominant hand on the rifle while adjusting the bipod with your non-dominant hand. - Thanks Rob01