Need some Metal Stock

[David V. Rogers]

I am in need of some thick brass, copper, aluminum stock for a
microwave dish project.  Thickness should be 0.2 inches or
greater (up to one inch), and needs to be at least 4.25 inches
square/diameter; I could use some at 3.25 inches
square/diameter.  Brass and copper are preferred as I need to
solder; will have to find another method if aluminum is
available.
Alternatively, could someone suggest some place I might buy this
at a reasonable price?
Second, does someone have any WR 42 or 34 rectanglar or WC 44 or
38 circular waveguide?  I need a snmall quantity.
73 de Dave (K9RKH)