The border allows you to bring back around $50 per-day per-person. Like if you go with two people and buy some $100 shoes, they might scowl a little bit because they know the shoes are for only one of you, not both, but they'll probably let you pass without charging tax.
There's no way you can bring a dozen people with you, or hang around Point Roberts for two weeks. You will be charged tax if you bring it in yourself from Point Roberts.
You shouldn't be charged a brokerage fee if you bring it across the border yourself, because all "brokerage" means is filling out a form. UPS doesn't like filling out the forms, so they charge people for it using convoluted schemes where they overcharge amounts based on the value of the package (which really has nothing to do with the difficulty in filling out the forms).
However, if you upgrade your UPS shipping beyond the most basic level, suddenly the stupid fees go away.
http://www.ups.com/content/ca/en/shipping/cost/zones/customs_clearance.html
Your $600-700 phone should get dinged with $56.50 worth of brokerage fees (plus the COD fees for having fees, and the taxes on the fees) using UPS's basic shipping, but if you upgrade to one level above basic, it'll arrive faster, safer, and cheaper.