It's not about the money. PPE like face shields are specifically used during procedures that involve significant bodily fluid, like intubation, which is the process of pulling or pushing a tube down a patient's esophagus. Going to to the grocery store does not require a shield.
Secondly disposable medical equipment, when used properly within a healthcare environment, is extremely wasteful. For most consumable items used in a hospital, they are covered in packaging with specific serial numbers and lot numbers that allow reconciliation if it's found that the goods are not sterile or have deficiencies. There is also a provenance or chain-of-command aspect that allows attestation of safety throughout the entire supply chain. While we might be talking about how to sterilize n95 masks, reuse face shields, and asking for donations of PPE from the public right now during a pandemic, the fact remains that in normal circumstances there is massive liabilities that hospitals and clinics would be subjected to if they started sourcing protective equipment from the public that could have been tampered with, may be slightly used and broken, or otherwise could cause harm to the patient and they'd be unable to identify the source of those resources. Everybody stocking a "handful" of PPE isn't a scalable solution to maintain a national supply.
This is one reason why we pay federal taxes.