Since last week (and for THREE more days--ends October 20th), Sunwing has been having a sale--buy one flight only ticket with Sunwing and get the second base fare at 50% off. Click here to go to the Sunwing page.
It's not a bad deal in fact, especially if you're looking to book a vacation during peak times and haven't done so yet.
Only problem is they're a charter, only fly out once a day, and depending on the route, may only fly out a few times a week at most. That means, if they end up cancelling a flight, they won't rebook you until the next time they fly and you're stuck wherever the cancelled flight occurred. If you have a deadline and must be somewhere, I'd never fly a charter airline.
Unlike a regular airline, charter airliners like Air Transat and Sunwing in Canada, and Spirit and Frontier in the US will not do what needs to be done to get you to your destination in good time--regular airlines will either get you out on the next flight with that airline or will fly you out with a competitor to get you to where you're going.
So if you have flexibility in your schedule, you may want to take your chances; otherwise stay away from charter airlines!!