Question: The flooring salesman keeps pushing "pre-finished flooring." Do I want this?
Pre-finished flooring has become quite a big deal in the last decade or so, and now (as your question implies) it is difficult even to find anyone willing to sell you unfinished flooring.
Answer: Pre-finished flooring is solid hardwood flooring that comes already sanded, sealed, and ready to nail into place. After the flooring installers have completed their job, literally the only thing you need to do is sweep up, and you're ready to go.