Well, the problem is if you're only ordering one cable, shipping makes the deal less attractive.
So a 30ft CAT5E cable is $3.30, and shipping is $5.11 for a total of USD 8.41. With the current exchange rate, you're probably looking at a charge on your credit card of right about $9 in Canadian, and you have to wait for it to arrive.
You just need to know how to look on NCIX.
Some items they have available:
25ft
http://www.ncix.com/products/?sku=51...e=TRIPP%20LITE
$4.63
http://www.ncix.com/products/?sku=52...%20-%20DT%20SB
http://www.ncix.com/products/?sku=66...%20-%20DT%20SB
$5.01
http://www.ncix.com/products/?sku=01...ELKIN%20CABLES
$5.44
Pricematch DirectCanada to $4.54:
http://www.shopbot.ca/r.html?catc=2&...odeid=14613405
If you need longer...
50ft
http://www.ncix.com/products/?sku=86...%20-%20DT%20SB
$9.01
I think we're done here...