I am quite familiar with the Seafarer line of sailboats. You did not stipulate what year the boat is, and Seafarer built several different boats around this length. I am guessing that this is one of their later boats.
For the most part, the later Seafarers were of mediocre build quality, and were so-so designs. One in good condition would make a reasonable coastal cruiser but given the build quality of these boats, it would take a lot to keep one in good shape and it would take a lot to bring one back that had been let go.
You have a lot of homework to do. You need to try to find out the age of the sails, rigging and engine. Combined these three items are worth as much as the whole boat.
If you really want to buy this boat, negotiate a price and get the boat under contract. Then you need to hire a qualified NAMS or SAMS certified marine surveyor to survey the boat. I would suggest that you visit the NAMS website
www.nams-cms.org. A good marine surveyor will go through the boat with a fine tooth comb and provide you with a real assessment of the boat's condition. A surveyor will also be able to give you a rough sense of what a boat in the condition of the boat in question is worth. Having a boat of this age surveyed is not an option. You can't get insurance without a survey. You want a purchase survey (more detailed) and not an insurance survey.
My sense is that an early 1980's era Seafarer 38 in half way decent shape, without a lot of upgrades would be sell for somewhere around $20,000. Putting one that has been neglected into up-to-date condition, could easily cost that much again.
Then there is the issue of whether this is the right boat for a beginner. In my mind, if you don't have a lot of sailing experience, this is too large a boat to learn to sail on. Learning to sail well on larger boats is next to impossible. Lastly it sounds like you will be sailing on a lake and these boats are not very good light air boats, and most smaller lakes have predominantly light and flukey winds. In other words this may be a boat that is ill suited to the venue.
Respectfully,
Jeff