Any Farm Supply will have the barn door hardware, no idea what company's are in your area.
Around here we have AG Supply, Tractor Supply, Agway, Southern States.
The few crystal knobs I needed I special ordered from a catalog in Lowes.
Checked at any salvage yards? The two I deal with have boxes of them.
Do not buy the cheap one's they have on the shelve. The screws and threads on the knob are horrible.
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