ground plates

Hi all,

I am looking to mount some rails on the Z axis for my router table
and the design I came up with would benefit by the use of flat plates.

I found a local supplier that wanted $60.00 for a 1/2 thick part,
8x16 inches. seems a little steep.

does anyone have any other sources ?

metalsonline has cold rolled, but did not have ground on their site.

Dave