Honestly you're not going to get a bite trying to buy $300 worth of Bitcoin and actually getting $300 market value. In the p2p world, there is always an upcharge no matter how you're trying to pay. Hell, even when I purchase sats on cashapp or sell them I lose a small percentage. There has to be profit involved for the seller/buyer. There's no benefit for someone to sell you the actual market value and waste their time just to help you out unless they're doing it as a favor.