I don’t know how you do your business, if it’s cash in hand or through the app. What I can suggest is having them send an installment if not the full payment on the paypal app! It’s really easy to use when sending a money request. Just set up a PayPal.me/ (your personal link) and send the request! If they send the money, you’re in business!
Just a fair warning its up to you what you choose to do but a few people have had claims denied with PayPal because Paypal and Offerup are not affiliated. I had to look up the TOS on Paypal because I used the payment instalments on facebook marketplace and that is fine because there is not a claimed payment processing company for marketplace. Just a fair warning..