Used OXO line 2 Standard rack system. Selling modular units @ $200 a barrel position. Can be 1 high to 7 high. Can hold up to 500 or 600L barrels.

A structure in which barrels are placed on a set of rollers. The space above each bung is free, allowing for work to be done on each barrel independently, in place. With the ability to access each barrel in the stack independently, it is possible to open, hot water rinse, fill, rack, clean, sample, rotate, and remove each barrel in the stack without touching any neighboring barrels. OXOline® is a modular system allowing assembly and configuration to meet the requirements of your space and work process. (From oxoline.com site)