US/Canada Customs Fees

Thanks for the responses. Actually this is a specific topic that I have not seen discussed on this forum. I will restate the question.
I am asking about carrying and declaring used, private sale items across the border from Canada to US (ie in the back seat of my car). If I purchased a used audiophile item with value of US$4000 (made in Canada), what fees if any should I expect to pay at the border crossing? I guess this question is directed at those of us who live near the border. Thanks again.

the only fee- carrying it over will be a brokerage fee which is peanuts compared to the cost of the amp. ensure it is made in Canada or US

I just read on US Customs website that they will collect a duty based on declared value. First $400 is exempt. The next $1000 (up to $1400) will have a duty of 1.5%. Anything over $1400 will have a different rate depending on location. The exemption can be doubled to $800 if you travel with a US buddy. God this is a great country.
Any other first hand experiences?

from my personal experiences, if you buy gears from US and ship it into Canada for perosnal use, you still have to pay so called "brokerage fee". I was charged by ups.
did this experience concurrent with yours?
thanks.

I purchased a Minidisk recorder from a Canadian seller value under $300, shipped UPS, when the UPS came to my door they charged me an extra $50.