I tried my first bookstore at Locomotion Video in Groton last summer. I didn't know the protocol for letting others know I was looking for cock to suck and it turned out I didn't need to because before I even put coupons in the video machine a guy walked up to the door stroking his cock. Five minutes later he stuffed his cock back in his pants as I wiped cum from my eye.
Since then I've been back there quite a few times. I've also been to Dan's and usually had good luck.