Didn't want to seem greedy, but since you mentioned them....
All joking aside, my fear of Chinese springs/valves/keepers/retainers is too high for their normal price. Wouldn't mind a killer deal on the CNC ones for me to load with my own stuff.
I would be willing to bet that even the Edelbrock stuff isn’t made in America. That being said I always changed out the retainers, keepers, and springs as part of my upgraded. We did have a chunk of a stock intake valve break off in one of my sons engines which required me to pull both heads to fix it because the piece traveled from number 3 cylinder to number 6 cylinder