This is actually and early 20th century, Arts & Crafts era, quarter-sawn oak trestle or refectory table. This does not date to the 18th century (aka 1700s). A trestle table has two to sometimes three supports linked by a horizontal cross-member over which a the table top is set. Trestle tables are the most common table form in the Western world since the early periods of furniture. The dealer likely meant to refer to this as a refectory table, however it does not infer or imply that the table itself came from a Priory or Monastery. If it did, then it should have come with provenance, or documentation of prior ownership in the form of receipts and/or photographs - not word of mouth from the seller. Check under the table top and body for any maker marks or labels. The estimate is based on actual recent past recorded auction sales of comparables. Retail 'asking prices' can be higher and vary.