Not sure how far away you are from the Houston area, but when I created deep scratches and dings on my longerons (the padding was not properly seated), I also started looking for local providers.
I searched and found a local Metal Supermarket that delivered 6061T6 0.75x0.75x0.125 to my door. They had all dimensions I could think of.
I paid about $40 for 2x175 in. Delivery charge was charged by the mile (30 mi one way) at approx. $45.
So $85 altogether for the two 175 in angles.