MemoryLanes...  you are wrong.  We pay more due to gouging.
We also pay more due to distribution agreements.

Most of the public lives within 100K of the border and if you look at the golden horseshoe you have 7 million people within 100k of the border. 

Example:
I recently needed a pump.  I went to my local retailer and he said "we used to buy these pumps direct.  Now they go through distribution and they are very expensive.  The manufacturer will no longer deal with us."

He quoted me 650 for the pump.  He quoted me 300 for a rebuild kit.

I went on the internet and I bought the pump for 218 US and the rebuild kit for 60 US and both these prices included shipping to buffalo.

We get screwed because they think we are stupid.  If DJT wants 800 per trip tax free I think I can go for it.  Most of the Canadian retailers need a shot upside the head and so do the distributors.