Tom, Look locally for someone that does boat top, they should be able to get most marine top & rail hardware.
We stock the type of hardware used for making tent bows, table legs, etc. For comparison purposes I charge $7.25 for the 7/8" tube stainless steel 90 degree elbow pictured earlier.
Here are some of the other types of hardware available.
What are you planning on making?
GPW, I'd have to think on it for budget attaching methods that would last
