Are you sure they're one of the cheapest for you? My experience with fiat payment gateway is that they charge a lot when I want to buy crypto, at least internationally. Even P2P offers are better compared to using a card to buy crypto from them.
So Paypal charges about 2% to buy/sell Crypto. Coinbase charges ... 4% to add money, 0.4% to buy/sell?
Update: I'm still not able to transfer crypto from Paypal to a wallet, but I was able to transfer money into coinbase for free via my bank acct, and trading fees are about 0.6% on CB.