For Lake Ontario I would recommend a CS 30/Express 30/Aloha 30/C&C 30 in that order. All of them can be had for $40K the latter three for less than 40.
They all sail nicely and will hold their value if you maintain them.
Of the four, none of them are ideal seaboats. You might be okay on the C&C 30 but the rest of the boats have rather flat bottoms for offshore sailing.
The issue is that the winds here in the northen climes and particularly on the Great Lakes tend to be lighter than those farther south, so what sails nicely here can get overpowered down there.
I really think you should focus on getting something suitable for the Great Lakes and I am strongly biased to the CS30 (I have one), as it's a very well-built boat with great performance and a nice roomy interior.
They are usually equipped with everything you need: refrigeration, propane stoves, hot and cold pressure water and decent shore-power wiring. Most of them have been barrier-coated already and there is a very active online owner's group.
The C&C 30 is also a great boat and will probably run about 10K less than the CS30. Not quite as much room inside and they are a tad slower but still great boats. There are more of them than there are CS30's.
Not sure if you have seen this site or not but it's good information for the Lake Ontario region. (Note that the estimated values are not too accurate - the site has not been updated for a while.)
Sailboats in Canada - 27' to 30' models