I used to work in Krakow for IT Comarch company, my salary was 7500 pln (5 250 net). Also got company car and private health care (for whole family). But, you can work for ANY company really, if you're experienced in IT department management. There is a lack of SAP specialists in Poland, if you know the system then you should expect 10 000 or even higher.
You shouldn't go below 5000 PLN gross. Gross to net is 0,7. That 0,3 are tax and social insurance and health care. But be prepared. Whenever you buy anything you pay 23% VAT. If you buy a gas, alcohol or cigarettes - then you also pay an excise. If you have a house in Canada and you're going to sell it for, let's say 300-400k CAD, then you're are a millionaire in Poland :) Krakow is a beautiful city, with awesome old town, there are really a lot of must-see places. Avoid Nowa Huta district and everything we'll be just fine.
And now, here's the deal :) I'm thinking about moving to Canada, with my wife. We got 10 years of experience, me as a key account manager, my wife as an accountant. Could you please tell us how much we can expect in Toronto/Mississauga area? Thanks a lot in advance.