I've been using the Jump-N-Carry JNC300XL for my portable power supply.
It's lightweight at only 10 pounds and has plenty of power for the drystar and other energy hungry tools.
Jump-N-Carry is a well known maker of sturdy power packs and at $55 to $60 the JNC300XL is an economical source of power.
http://www.nationaltoolwarehouse.com...qx/product.htm
.