The most expensive guns sold on GunBroker in May 2026 highlight continued strength in the high-end collector firearms market, led by transferable machine guns, historic Colt Thompsons, and scarce NFA conversion devices. With top sales ranging from $21,675.00 to $52,515.51, May showcased strong collector demand, competitive bidding, and premium prices for some of the most sought-after firearms and transferable assets in the marketplace.