You might check out B-Line strut hardware. We use it at work for all kinds of stuff.
http://www.b-line.com/product/PDFLibrary/strutsystems/index.htm
The rollers are called trolley fittings.
http://www.b-line.com/pdf/catalogs/ProductInformation/SS08-PDF-WebPI/Fittings-MiscellaneousFittings.pdf
We get it from Ashby Plumbing and Heating in Berkeley.
The owner, Glenn Kunishige, is a good guy.
http://www.b-line.com/product/PDFLibrary/strutsystems/index.htm
The rollers are called trolley fittings.
http://www.b-line.com/pdf/catalogs/ProductInformation/SS08-PDF-WebPI/Fittings-MiscellaneousFittings.pdf
We get it from Ashby Plumbing and Heating in Berkeley.
The owner, Glenn Kunishige, is a good guy.