If either or both of you have the ability to complete and organize fairly detailed work, and your situation is such that you have your every day "boy-meets-girl" scenario, then by all means do it yourself. If you want the added comfort of a professional's eye, Zouk's recommendation is spot on.
If, however, you have a history with immigration (Canadian or otherwise), if you have a history with the long arm of the law (Canadian or otherwise) if you did something in the past that did not result in you brushing up against law enforcement but might have? Bite the bullet and pay for some decent, knowledgeable, trained representation.
I cannot stress the "knowledgeable" and "trained" enough. Inasmuch as not everything that glitters is gold, not everyone who holds themselves out to be an "immigration consultant" is worth the paper their name is printed on. Hire yourself someone certified by the appropriate body (law society or immigration society or both), with experience in the type of situation you are in.