Can I buy an Air Ticket from India if I am travelling from Toronto?

I guess a two way ticket from India would be cheaper, so can I buy a two way ticket from India, instead of buying it from Toronto.
(Online of course)
I want to travel Toronto -> Delhi and Delhi -> Toronto

If you are going to buy it online then the price will be the fixed online price, for the routing that you want. If you want to buy the ticket through an agent in India they will have to pay a premium to originate the ticket in Toronto.

when we buy air-ticket online or from agent in Toronto, they will give us 'published rate' which is higher than if we buy the ticket in India.
Yes! we'll get cheaper ticket if we buy in India or from agent in India.
So call/email any agent you know in India, pay them by wire, than ask them to send you the booking ID, so you can issuing the ticket in Toronto.