3 exams, the SAMRA, SARON, and INRAT.
You will also need to take a checkride. It will be a multi-IFR checkride that must include at least 1 ILS, 1 NDB, and a hold, which for me was an NDB. All checkrides are on a point system. You must make a certain score on it to pass.
Of coarse, you will also need a Category 1 medical. Which is slightly more stringent than the FAA's.
Depending on which Transport Canada inspector/examiner you get, it can be relatively painless, or the exact opposite.
Good luck
Cost is relatively inexpensive.