depends on what kind of placement and which program you are getting the co-op from..you can make anywhere from $11 to $25 is what I have seen depending upon the company and the role you will be doing..there may be some employers who won't pay you anything as well..
Contrary to popular beliefs on this thread, Co-op placements are paid internships - atleast most of them are. In engineering and business in universities (such as UofA, waterloo, UBC, Toronto and few other colleges) ALL OF Co-op placements are paid.
Yes it is correct that you can be paid anywhere between $12 - $28 per hour depending on what you are studying. If you are in engineering it usually starts from $18 and can go upto $30 per hour.
The most important thing to remember that Coop placements like jobs are difficult to find--so don't plan on using that income to fund your stay or you might be dissapointed