Hi Adrian,
I've done a cost analysis for all clubs and marinas west of the ABYC to Oakville. I have a spreadsheet with all my numbers, including amortizing the initiation fees over different number of years. I can tell you that it is, by far, cheaper to join a yacht club than to keep your boat in a marina.
I would prefer not to share all of my numbers publicly but would be happy to discuss them offline.
The biggest aspect of choosing a club is that you have to live with your decision for years in order to justify the costs. That means you need to do the leg work to visit each club and get a feel for the membership. In our little Lake Ontario Contessa Association, there are at least 5 clubs represented so you can get some second hand opinions. Everyone has different needs so you'll need to choose one yourself.
I am a member of National (but my boat isn't), I'm also a member of Etobicoke. They are both excellent but VERY different in nature; Different cultures completely and each group is quite happy with their own benefits and drawbacks. It all depends on what you want to get out of your club.
FWIW, my calculations yielded costs from $1,281 -> $5,000+/yr for a Contessa. However, the cash outlay is quite a bit higher due to recoverable debentures etc. If you would like to meet at NYC or EYC for a beer, I would be happy to review my numbers with you in as much detail as you wish.