Congratulations on making the decision to spend nearly all of your free time and money on the worst financial investment of your life!
... but probably the most rewarding.
You are one of the very few in these forums who is actually taking the gradual and IMO best approach to boating. You started small and are moving up.
Having bee exactly where you are, I agree with everything that barry says and will add that
1. Nearly every boat in your age and price range will need work of some sort. That's ok, I've owned 2 early 80's boats and they are a great value. I'd recommend buying something is reasonable condition and resolve to do all the maintenance yourself. You will save money and learn your boat. Be willing to make mistakes and askk lots of questions (SailNet is a great resource)
2. I am very partial to Sabre, but Tartan is great. Cal made a great boat at that time. Catalina is also a great choice, but the Cat 30 may need too much air for your purposes.
3. For this vintage, pay attention to the area surrounding anything that goes through the deck. Core or rot issues abound in this vintage if the caulking was not regularly maintained. If the sails are original or more than 15 yars old, replace them. They may look fine, but they're not. The performance improvement with new sails will be dramatic. The cost won't be that bad and your arms will appreciate the diminished weather helm.
PM me if you have any questions regarding Sabre.