actually having a surveyor come out and verify already in place lot markers [burried survey points] is not, on the scale of these things, very expensive. When $millions and your possession of your future home are at stake, a couple of thou is really cheap.
When I was practicing law, I had a minor specialty in border disputes, rights of way, adverse possession, etc.
People who were too cheap to pay a surveyor generally found that a lawyer was far, far more expensive!