As far as boats go with the big 4, Catalina,Hunter, Beneteau, Jeanneau. The dealer network on Lake ontario is excellent. Beneteau being the best and hunter the worst (for service). The Beneteau dealer takes care of the brand regardless of boat year. How many dealers give free tickets to the Annapolis boat show every year? I didn't buy from him either. Private sale.
If i were you i'd look at some Jeanneau's they may fit your bill. Keep in mind that cruising the lakes is like cruising the Ocean. Lake Ontario can get mighty rough in the spring and fall. You always want to be on your toes.
As far as marina's or yacht club. Yes, you will get more service from a Marina for the most part. I stay in a marina, yet, i have a full Yacht club membership ($350). Why? Reciprocals! On lake Ontario, especially the south side, finding a cheap berth/anchoring spot can be difficult. You will save money if you cruise the lake as a Yacht club member. I'd rather pay 0-$20 a night versus $80-$160 a night. If you cruise on the lake it's worth it and you will break even at the end of the season. Plus, you get to meet some great people by visiting other clubs. Other than Toronto, the rest of the lake has small clubs that are basically middle class joints.
Best of luck, There are a lot of GREAT boats for sale in your neck of the woods. You should find a broker you trust.
2000 Jeanneau Sail Boat For Sale - www.yachtworld.com
1997 Beneteau 400 Sail Boat For Sale - www.yachtworld.com
1996 Beneteau 36s7 Sail Boat For Sale - www.yachtworld.com