IMA has a British 10 pounder breech loading Screw Gun for sale. Dated 1902, fully functional and only $35,000.

picture of Screw Gun

In a story on, a Colt 1883 10 barrelled Gatling Gun sold for $172,500 at a Civil War, firearms and militaria auction at Fontaine's Auction Gallery in Pittsfield, Massachusetts, on Aug 15th, 2009. A second Gatling from 1874 brought $69,000.

picture of sold Gatling Gun