Vintage Stow Davis Executive Desk

This Stow-Davis desk was purchased at a yard sale by my father-in-law in the early 60's. I have been told it is mahogony. There are 7 drawers and when closed in a particular sequence the drawers lock and must be pulled on in a particular sequence to open. The top could usesome sanding and would be beautiful restored. The bottoms of the legs and drawer knobs are brass. I am wanting to sell but have no idea where to start for an asking price.