I’ve been buying and selling stuff online on various gun forums for well over a decade and the good old USPS money order has always done the job. Buyer sends money order, you receive it and send item.
Another thing to consider with paypal, many of you guys buying and selling online process your payments using friends and family, if you read the terms of service they will fine you for using friends and family to sell goods and services as well. They have also been known to freeze your paypal account holding your entire balance as well. Your paypal account is linked to your bank account, they will simply fine you and remove the money from your bank account without even giving you a heads up first, it’s a well known issue.