I owned a CS30 for 4 years
They are exceptionally solid, well built boats. However, they are very different from modern (say after 1995) boats. Unlike the present-day boats, the stern is narrow - the width is not carried back as in Hunters and Beneteaus. As a result the boat tracks better and does not slide off following seas, but has much less cockpit space and an inadequate (in my view) berth. The CS boats go upwind very well, but the tall rig and small mainsail make them pigs off the wind. If the boat does not have a gennaker or similar, you will want one, particularly with our often light Lake Ontario summer winds. The original equipment does not include roller furling; if you don't have it, you will want at least two head sails, 3 would be better. No refrigeration is a pain, but the icebox is well insulated, and if you keep it full, will keep stuff frozen over a weekend.
I don't think the price is too high if the boat is sound, the engine runs well, and sails are not blown out. Things you want to know for sure: when were the sails replaced (can't be 30 years old, I hope) how old is the running rigging, when were the old analog instruments replaced? That plus a reasonable survey and you're good to go.