I'm sure its frustrating to get no-where.
But google really is the answer. (simply too many applications for metric fasteners these days)
....or you local yellow pages . a chat with a real person at any good hardware store should help put you in the right direction.

some specifics to add.
your address/city ?
screw diaameter ( 6 mm)
length ?
pitch ?
stainless alloy ?
head type ?

as others have been suggesting ..
maybe you're searching for the wrong key words.
fasteners/screws/ machine screws / metric stainless.
every car in the world uses them now & canada gets them from somewhere.
no worries.
-bill

Call Brafasco in your local. Here in Kingston Ontario they are in stock. I have been them there for years.
Stan

They're not as common as some would have you believe. I only know of one place in Ottawa who carry a good selection of lengths: http://www.ottawafastenersupply.com/

Peter

I think grainger.com will ship to Canada.

http://www.grainger.com/Grainger/machine-screws/screws/fasteners/ecatalog/N-8n0?op=search&sst=subset#http://www.grainger.com/Grainger/machine-screws/screws/fasteners/ecatalog/N-8n0Z1z0ny6vZ1z0ny6rZ1z12nykZ1z0o17jZ1z0nwojZ1z0nsobZ1z0o0wm?Ndr=basedimid10071&dojo.preventCache=1339687522735&sst=subset

Here in Canada we live in igloos and eat only seal blubber. We rarely see metal screws.
When I google 'fasteners Canada' I only get 7,130,000 results.

You will need to get these screws shipped from a foreign country.

Fair enough. Please send me the website of a Canadian distrubutor of an M6 Stainless steel screw (or bolt) pan head philips 20 MM long, from one of the 7.1 Million hits. The first poster has not stepped up to the plat, maybe you will. My point is this is hard to find over the internet if you are looking for a Canadian shop.

BTW, I was able to find a pack of 50 screw from West Marine for about $US 20, shipping was close to $US30 - not including duty and tax. I need 4 screws, this seemed a bit expensive.

However, my kiteshop did help me to locate a local fastener shop here where I bought 8 screws for $CDN3.60. I was also told by a buddy that Canadian Tire stocked them, but they were out at the shop I went to.

Ace hardware -you have them in Canada - they will have M6 S.S., but with Allen heads.
Mcmaster-Carr -they have every bolt in the world -they will ship to Canada- 25pc min order