Anything coming into Canada valued at less than $50 is Duty free.. The only way I've found to take advantage of this and avoid broker fees also taxes is to always ship via regular Postal mail.. Also make sure to tell the shipper to note only the value of the item itself (not w/ shipping etc) on the little sticker that goes on the outside of the package..
If multiple items from the same place exceeds the $50 thing, it's worth breaking it up into individual packages..
Also it's not a foolproof way either as every now and then you have to pay a fee and for no good reason too..but I've just always paid them as lots of stuff w/ even high values seem to slip through without incurring duty and texes anyway..
~ Pete