Yes, Vincent rents the guns. I think he charges an extra ten dollars or so, but like everything in Jamaica, it's all negotiable. The scooter I rent privately from Garrett at Seastar Inn. He usually charges $30 per day, a little less for me 'cause we've known each other for so long.
You can also rent 'em at several places on the Cliffs and beach for about the same price, though I try not to spend more than $20 per day, and they usually say OK 'cause I make a deal for the duration of my stay.