Y usually runs about $125 USD and J runs about $40 more than that. I don't know if a TA can do better than those prices. I've purchased off Expedia and through TG direct. It's about 1.5 hr flight. The food IS good for such a short hop. J gets you a better seat and meal. Y has been tight, I find, but I'm tall-ish (6'2").
I was suprised that TG didn't serve any alcohol on domestic J flights. But nice iced coffee!