I'm not an expert on this, but here is something worth consideration...
We had a boundary dispute with a new neighbor who moved in and claimed that our fence was on his property. The fence had been there for 18 years, and we agreed with the neighbor on where it should be built. This was a constant point of contention from the new neighbor, and was years of passive-agressive behavior on his part. After he came over and started cutting down trees on our property, we finally decided to take more formal action.
We went ahead and had a surveying company come out and take some GPS readings of various landmarks (trees, fence posts, retaining walls, driveway) along the property line. They then used existing survey monuments in the neighborhood to calculate the location of the property boundary in relation to those landmarks. They provided us with an official (stamped) exhibit map that showed the "calculated" property line and the mapped features. We sent it to the neighbors by certified letter that basically said, "We had a professional surveyor locate the property boundary...blah blah blah, the issue is resolved." We deliberately did not say "We had the property surveyed", because it wasn't technically an official survey recorded with the county.
This only cost us a few hundred bucks 5 or so years ago. Our understanding was that an official survey would have been significantly more expensive, partly due to the recording fees.