Don't even mention the exchange rate to us Canadians!!!
In May you should be able to get some Westjet flights for a good price. Not sure about Air Canada or how long they continue their summer service to Aruba. Our friends paid about $550/$600 pp on Westjet last May and they weren't coming from Toronto but not too far. The additional cost was minimal but not sure how much extra they add on from Edmonton and St. John's. Usually when you book say Edmonton (as an example) to Aruba it is not priced as it would be a full price Edmonton/Toronto and then Toronto/Aruba. There is an extra charge but normally not outrageous.
Many hotels have specials in May as its not high season. I would consider contacting Westjet Vacations and Air Canada vacations and get some ideas on pricing if they have them yet. Of course the issue is that prices are going to be based on our dollar as they need to block the rooms in US$$
BTW, if it is this May you are looking for both AC and Westjets flights are loaded so you can easily check the flight prices.