Two 7 foot pocket door tracks. Antique hardware dealers sell them for $200 each. Buy these and attach to a wall to make a vintage authentic (steampunk style) picture or chair rail!
Three "Lane" design Trolleys, typically sell for $75 each.
$50 for the lot.
These are all antique but still quite functional hardware either as repair or replacement hardware for pocket door pairs (though another trolley would be needed) or to create a single 7 foot wide door in a garage or barn.
A number of companies made these in the late 1800s and Lane Bros in New York made improvements in their design including the mini-roller track on the trolleys as these have.