Not a cuemaker, but quite experienced with business practices.
The opposite side of this coin is that if you help your supplier by sending them new business, they will stay in business and which helps keep you supplied.
If you shared all your sources, you could go out of business.
I don't know if scarcity is a factor in your business.
If your business relied on limited number of good materials and you keep sharing the source of your materials, someday you'd wake up and find out the price for those materials have gone way up and price and the grading system just became a lot looser. Suddenly the quality has gone down and the price has gone waaaaay up.
That happened to our old birdseye and curly maple supplier . My late friend shared the source his old friend who had a lot more money than he had. His friend made a phone call to the supplier and told him he wanted pallets of his woods at higher prices he was offering .
Let me not even discuss what happens when someone says , " Let me know your source and I'll keep to myself."