ecmonster via eBay offers this 6-Foot Wooden Sliding Barn Door Hardware Track Set in Black for $39.50 with free shipping. That's $8 under our February mention and the lowest price we've seen. (It's the best deal now by $3, outside of the mention below.) It includes a 72" rail, four wall hangers, two rollers, two door stops, and floor guide. (Door is not included.)

A close price: liho-us03 via eBay has it for $40.99 with free shipping.