Reservationadvisors.com has a rating of 5.0 stars from 2 reviews, indicating that most customers are generally satisfied with their purchases.
I booked a flight from Denver to Las Vegas and it was just for 112 USD with the frontier airlines and they helped with the seat selection too.
I booked a ticket with them and there was schedule change but they helped me to get the another flight for same price at last minute. And they helped me with the seat selection as I have knee problem and need space for my knee.