It is better to purchase ammo from vendors, but it can be useful to waste some bolts on ammo when it is absolutely needed, such as in boss fights. In Ratchet & Clank, the PDA is especially useful during the final battle as ammo, notably Devastator ammo. In Ratchet & Clank: Size Matters, Ratchet could purchase it at a Gadgetron vendor. However, the Static Barrier's ammo was not available to buy from this version of the PDA, despite it being a Gadgetron product.