If you would like to build your own STEEL frame you can purchase a basic set of STEEL angles from VantagePoint Outfitters and purchase common 1" electrical conduit locally. The kit will include six end pieces and three connectors which will allow you to construct a three truss frame. If you want to add another truss buy three more CONNECTORS.
Basic Kit = $135.
Individual Connectors = $15. ea
Individual ENDS = $15. ea