Hello 'patty55ca',
The differences in prices may depend on the service that is chosen. Have you seen the
Canada Post website where you can get parcel rates?
http://www.canadapost.ca/cpotools/apps/far/personal/findARate?execution=e1s1
And the USPS site:
http://ircalc.usps.com/?country=10054
Your seller seems quite reasonable and fair to me. There are so many of the other kind.
He offered you the choice, fine, and you opted for the cheapest and slowest service.
Obviously you are not in a hurry, - but the $30 would have been a bit faster. Definitely not
worth the extra $$, no, but you are fortunate to have been able to decide for yourself.
At least that is what I understand from your post.
<< I have a real problem living in Canada buying from fellow Canadians and getting charged US currency >>
You are not alone, -- a lot of Canadians feel the same way. The thing is, Canadian sellers will
tell you that most of their business goes south of the border. Canada has a small population so
in order to stay in business, sellers need to sell to the US. And in order to sell to the US,
Canadians need to list in US dollars because it makes Americans happy. Canadians are generally
more internationally-minded and are used to thinking in other currencies, whereas Americans tend
to be a bit prickly about wanting to buy in the only currency they are comfortable with.
There are sellers in the UK and Europe who list their items in US dollars, -- trying to appeal to the
large American market. It's just a necessary business practice. The same way almost everywhere
we go in Canada we see signs in shop windows announcing "on parle français" or "hablamos español", etc.
You are right, though, that ebay is not the cheapest place online for books. It depends on the title, too,
of course. Choose "Worldwide" from the Location option on the left, and then "Price plus shipping"
in the Sort bar.
Otherwise, there are other places to go, - amazon, abebooks, and my favourite - bookdepository.
At that, however, you won't find the sinfully low prices (considering price + shipping) anywhere online
that you'll get from flea markets and thrift stores, so that may not have been the fairest comparison.
Not everyone is as mobile as you clearly are, so for those who are unable to 'scour' these local vendors
for goodies, being able to click a few buttons and have the books arrive at the door is still a pretty good
deal at any price.
All depends who you are, I suppose.
Happy reading. 
"Canadian sellers make more money charging in US funds considering our dollar is usually worth less"
???
Not really. That is a misconception.
Most Canadian sellers price an item based on its market value or, in the case of auction, the market value is determined by buyers collectively.
If the item I want to sell is worth in my opinion Cdn$ 50, I have a choice: I can list at US$ 46 or Cdn$50, both representing more or less the same value to all buyers, based on current currency conversion.
If I price my item at US$50 (Cdn$ 54) then that would be more than the Canadian market is willing to pay and my item will not sell. So a seller would not "make more money" by overpricing an item. It would simply remained unsold.
