First of all, let me clarify that here in Pakistan, the bank will charge you some amount for the issuance of the draft (it could be either a fixed amount or a percentage of the draft amount depending upon the bank with which you deals). In Canada, they will not charge you any amount because here in Pakistan, they will charge you because you are drawing money from their bank as well as using their services. On the other hand, in Canada, you will be a new source of funds for the bank so obviously, they would not charge you.
Now, with regards to buying a ticket on a credit card. I don't know how much you have traveled in the past but i am suggesting you all this on the assumption that you have not traveled too much in the past.
You can buy a ticket on a credit card on the same price but there are many travel agents who charge 1 or 2 percent extra so that you have to pay extra otherwise, there would be no difference in price either you buy it on cash or through credit card.
One very important tip is that i dont know if you are aware of this or not but there are several routes through which you can go to Canada provided as follows:
1- Emirates (Pakistan to Dubai and then to Toronto)
2- PIA (Direct to Canada)
3- Etihad (Pakistan to Abu Dhabi and then to Toronto)
4- Turkish Airlines (Pakistan to Istanbul(Turkey) and then to Toronto)
5- Gulf Air (Pakistan to Bahrain, then to London by Gulf Air and then to Toronto by Air Canada)
6- Qatar Airways (Pakistan to Doha (Qatar) and then to London by Qatar Airways and then to Toronto by Air Canada)
If you want a cheap route, then check Turkish Airlines, Gulf Air and the last route of Qatar Airways. Although, The route of Gulf Air and Qatar Air is very long and hectic because it has an extra stop on London but if you want some saving then its a one time fatigue and you can save that amount for Canada. Emirates, PIA and Etihad will be the most expensive routes.
Finally, but the ticket from a travel agent and not from the airlines office because there is a lot of difference in prices of the airline office and the travel agents and travel agents always offers cheap tickets whichever the airline is.
Its a long story now but i am sure, all of your queries will be satisfied by this. If you need any other help please feel free to contact me.