buying a car from the U.S (i'm from canada)

ive been looking for a car for a long time, and there is nothing of what i want here in canada, and if it is the price is ^^^^^. but i have finally found what im lookin for in the states. i know ill have to pay a bit more for exchange rate, and when i bring the car to the border going back to canada, im sure i will have to pay duties on it. But i need to know how much, and what other crap there gonna set me up for at the border. if anyone has done something like this before, or no some one who has, please give me all the info on what happened and what and how much has to be paid. This is SO important for me, so any info is a great help. thanks