Ericson makes a good boat, I sailed a 25 centerboard-version many years ago, a nice boat but very tender, the keel model is probably a fine sailor.
That said, $11.5K is a lot of money for this age/size. The boat may be worth that, if in prime condition and well-equipped.
My advice is to hold off on the survey and first look at that boat, and similar listings from
New and Used Yachts for Sale - YachtWorld.com. There are several Ericsons in your region, plus look at similar boats like C&C and Catalina.
These are all good makes. After you have looked at 5-6 boats, you can develop a much better feel for value and for what makes you smile when you see her...the most expensive boat may be the best value...or may not. After you've seen a set of boats. make a reasonable offer on the one you like, reasonable being based on how you compare that boat to the others in value. Do a survey only after you have an accepted offer.