Finite resources vs Infinite resources

[Octopus-Pancake]

So I found some low level uniques I really like and wanted to upgrade but having a bit of trouble locating the materials.  Is there a finite number or at some point do the resources respawn?

[thelee]

afaict resources don't respawn, but merchants should generate mats for sale, i think that's an infinite (if slow) source.

[Octopus-Pancake]

ah ok thanks