You're a newbie, That hasn't been active in almost two years.

There is no guarantee or way to verify that your funds are clean. The best someone can do is verify that you have enough balance to cover the transaction, but not that you sent it from balance and even if you send it from balance that only protects from CC chargebacks, not PP chargebacks.

The only requirement that would attract a reputable trader, would be if you are willing to wait the 60 or 90 days so that an unauthorized chargeback can no longer be filed. Nobody is going to accept your $500 of Paypal; there is just no safe way to do it.