I seem to do a lot more prebuys these days than years ago. Most are out of town, with the recent one being completely across the country. I typically do the test flight and delivery myself, but every deal is different.
Like some have said, there’s a big difference between a good prebuy and an airworthiness inspection. On a prebuy, my goal is to evaluate current conditions and any items that will impact the buyer’s wallet in the future. Misrepresented items, conditions, and logbook discrepancies are not at all uncommon. Unfortunately, misrepresentation seems to be an increasing trend. It’s not always intentional, but it usually doesn’t benefit the buyer, and therefore needs to be properly identified.
As some have pointed out, a prebuy is not regulatory in nature, it’s not an FAA regulatory requirement that is. It’s not a maintenance practice that’s learned in A&P school. Therefore, a number of A&P’s aren’t comfortable with the prebuy. Some don’t exactly understand the difference, or might not be experienced in this specialized area.
Logbooks: I almost always make a log entry. Usually the entry is just for the removal and replacement of the oil filter. Removal and replacement of upper spark plugs for compression check, etc. All of which are “due to prebuy requests.” I do not list any findings in the book, only the work accomplished IAW the applicable manual, along with any new parts installed, such as spark plug gasket, etc.
I’ve never done a prebuy that didn’t save the buyer more than the cost of the prebuy itself. The last one was on a early 90’s Bonanza. Without the prebuy the buyer (very experienced in purchasing) would have paid considerably more. He was extremely pleased with the outcome.