Yes this is a good way which I never used. Last time an agenct called me and directly asked me how much salary I wanted, I said I was not sure the condition in Canada, but he still prefer to let me provided him an approximately number. Because it was a contract position, so I told him the hourly based should be around 25-30 bucks, maybe my request is too low, he never reply me again, and this position is very similiar to what I did in my former company.