I use KINEK located on 6th street in Niagara Falls NY. About 5 minutes from the rainbow bridge exit.
On average costs me $5.00 usd per parcel. Costs nothing to set up, you do it on line.
Ordered almost all I need for the mustang, my bikes heck even a kitchen sink once. Most US companies ship for free.
I declare all and pay my taxes like a good Canadian should. In many cases they waved me through without taxation, bonus.