I am looking to buy a pcp to add to my collection of springers and pumpers. I am completely a noob when it comes to PCP's so for now I am just looking at entry level guns. Will be used for small game hunting.
Is your $150-300 budget the cost for just the gun? You also need to factor in the cost of a tank, hose, and gauge. You could just start with a pump for now but you will realize you will eventually be buying the tank, hose, and gauge which could double your $300 budget. If you go the tank route, you need figure out how to fill up the tank which could cost additional $300 or much much more depending on what you choose.
I killed many squirrels as a young man with a .177 springer. A good accurate .177 PCP is enough for that use. I have a SPA Varmint .177 (same as Diana Stormrider) that is powerful, accurate, light, and easy to fill with a hand pump. I no longer hunt but it would be one of the first things I reached for to take a squirrel. Wish I'd had something like that 50 years ago.