You can not claim the taxes that you pay for your purchases, unless you have a business and you use it for your business purpose. The tax that you pay on top of the purchased merchandise is a sales tax and is usually called HST. No matter how much you spend for shopping, CRA will pay you some amount next year to compensate that (in Ontario, not sure about other provinces).
Some people prefer to buy their stuff from Iran and in most cases they are cheaper there. But please don't forget that the waranty is very important too. Not every item has an international waranty. If you buy a MacBook from Future Shop in Canada, for example, then you have 14 days to return it back without any question, just in case you did not like it! And also it has its own manufacturer's waranty. If it is broken during the waranty time, you will call them and the rest is very easy. Or, you can buy an extended waranty from the store with a low price. In this case, you can even replace your device in case it is broken during the waranty.
To make the long story even longer, if you have already a laptop or iphone or such, bring it here. If you are going to buy one, think twice. You buy it in Iran, it is cheaper. You buy it in Canada, you will have peace of mind.
