If both of your parents formally renounced their Polish citizenship, and you were under 16 at the time the decision was rendered by your local Consulate/Embassy, you automatically lost your citizenship as well. This means that regaining citizenship will involve the full bureaucratic treatment and a plea to the president for special consideration. However, in all other circumstances (no formal decision from the consulate/embassy, only one parent renounced, you were 16+ at the time of decision, etc), you would still be a Polish citizen and getting a passport shouldn't be much more hassle then applying for it at the consulate, the same as any other citizen.

BTW, if you submit your application to regain previously renounced citizenship in Canada, it will cost you $400 (or at least it did a year ago). However, if you have a residential address in Poland and can apply from there, it will cost you around 10zl ($4).