There are fast and frequent train connections direct from Frankfurt airport to Cologne (with intermediate stop in Bonn).
Schedules, pricing, and advance purchase  here:
http://reiseauskunft…

Regular priced ticket is from 41 to 56 EUR each way, that is a round trip by train will run you another CDN 120 – 150.

Find out if you can get “Rail and Fly” supplement to your ticket. It will probably cost much less then above. (With “rail and fly” you get extra plane ticket coupons that are valid as train tickets from/to airport to/from any German train station on the dates on your flight.s This product is not being advertised much outside of Germany, but it does not hurt to ask.)

Thank you, I will look into that…
 
My other question is… Do you have other suggestions as to how can I reach Cologne/Bonn using different route?  Say is it cheaper if I going to London then Cologne?

What’s the cheapest way you can get to Europe at all?

The sites mentioned on other threads are Zoom, Canadian Affair, FlyGlobeSpan, Air Transat, Exit.ca, Selloffairfares.com among a few.

So look for the very cheapest way you can get to Europe anywhere.

Then look for budget flight options within the UK and continental Europe from www.whichbudget.com .

However, particularly with a low-cost carrier like those mentioned above, I would not try any close connections, because delays do happen. So I’d recommend you do an overnight going and coming in whatever city you land in or are departing from.

For example, Don posted a cheap fare to Manchester from Toronto. Then with TUIFly you can get to Cologne from Manchester (although I didn’t check the price).

What’s best is going to depend a lot on your dates and the length of your trip, so investigate widely.

Try www.condor.com too.  I’m flying with them direct to Frankfurt from Halifax in August.

Thank you all for the information,  it helped me alot!  I love this site! AWESOME!