A proposed ban on bump stocks, like those found on guns in the hotel room of the Las Vegas Strip shooter Stephen Paddock, coupled with the decision by two major retailers to pull the items from sale, has sent demand — and prices — soaring.

The Trace has been unable to track down any retailer that has any of the devices still in stock. On the auction site gunbroker.com, the bidding for bump stocks, which allow a shooter to fire a semiautomatic weapon at nearly full-auto speeds, has risen to four or five times the accessories’ previous retail price.

One auction for a single Slide Fire brand bump stock designed for an AR-15 has attracted 15 bids, driving the price to $830. A left-handed version has fetched bids of $755. Before the company stopped processing orders and its device was still sold by stores like Cabela’s and Walmart, Slide Fire stocks typically retailed for about $200.

A nearly identical device made by Bump Fire Systems, a company that has since gone out of business, has shot up to $555 with nine bids. When Bump Fire was still in business, its stocks sold for just $99.

The devices are also selling for far higher than the listed price on Armslist, a popular online gun marketplace.

The prospect of additional regulation has long been recognized as a surefire way to send demand for guns and accessories soaring. Military-style semiautomatic rifles became huge sellers during the Obama administration amid fears of a renewed federal ban on assault weapons. Sales of those rifles have cratered in the Trump era as consumers no longer fear the guns could soon be harder to get.