You're supposed to buy one for each vehicle. When you buy 1, they give you a few dollars off on the second one. I'd say you will probably get your money's worth if you ride much at all. Custer State Park is fantastic, and of course there's other state parks around, including the Lewis & Clark area around Yankton, and a few different parks in NE South Dakota, Sicca Hollow, Roy Lake State Park, Fort Sisseton and others. Welcome to SD! We try to ride in the Black Hills a couple times a year if possible, along with whatever other rides we get in.