Buying plane tickets from Ottawa to Victoria?

I need help. My friend and I need to buy two tickets from Ottawa ON to Victoria BC for next month, for flexible dates. We will be traveling together, need return tickets, and can flights any time of day/week. We will be spending at least a week, possibly 2. Problem is, we dont have a credit card. Do travel agents cost more? Do they not find good deals? Airfare is our main cost here and we want to save as much as we can, and have seen rates online from 200 to 1200 each for round-trip and we dont want to get scammed. We have never traveled alone before.