Quite possibly true; but investigating corruption seems like one of those activities where you pretty much have to chase down what you can, even when it doesn’t make sense on a cost-recovery basis, lest you create the (obviously bad) norm that all corruption that’s either relatively penny-ante or sufficiently obfuscated is basically OK.
As someone(reluctantly) involved in maintaining inventories and handing out hardware I’m very much of the philosophy that micromanagement is more costly than just treating people like reasonable adults; but only in a context where you don’t have reason to suspect that someone is trying to play you and where you’ve minimized the ability to actually get anything worthwhile out through the cracks.
Once someone gets to pick their own vendors and name their own prices you are clearly in a different position from just not auditing people’s claims that their $30 mouse/keyboard combo needs a replacement and storing those in the supply closet rather than behind an IT approval process.