You certainly have the right, and probably wise to get a return commitment, in writing.
Also, even if listing says 'working' ... write seller via the service, i.e. eBay, Reverb ...ask questions, and get clarifications in writing which you can then refer to if a dispute arises.
Note: eBay, PayPal, Reverb have buyer protection. PayPal: get an invoice from seller for the item(s) via eBay so you can pay for 'goods and services' (not send money to friends or family which is not protected) avoid using zelle if you can.
The extra fees for protection have gone up; reported sales/taxes are more of an issue, you might need to offer to pay the extra fees involved with the system like PayPal.
Fund paypal with your best credit card so you have the CC's 'fraud' protection. Sometimes I call the CC company prior to a purchase to confirm coverage and ask what might be needed for a successful claim.
CC Fraud often has a 14 day delay, so get 30 day return privilege's if you can.
If you buy a warranty, check if it is transferrable, might help with a re-sale