Doc's idea meshes with Josh Gordon's surtax proposal.  See:  http://torontolife.com/real-estate/qa-joshua-gordon-researcher-blames-buyers-rising-home-prices-toronto/.  Both make sense.

Re KM1's comments, a start would be to set the bar at higher surtaxes/property taxes for purchases made with "non-Canadian-taxed" income.  This is doable if the provinces and feds cooperate to make all RE transactions contingent on a thorough review of income tax filings of the purchaser. That's the only way to know if Canadian income tax has been fully paid on all the money being used for the purchase. Money from outside Canada would only be suitable if it was duly taxed in a country that has a fair tax agreement with Canada. "Gift" money would only be suitable if one could show the source, and that source's income tax filings revealed tax duly paid in Canada or in a country with a fair tax agreement with Canada.  No sale if taxes paid aren't commensurate with the RE purchase price.