You should just Craiglist your GPU or Facebook market place. Right now GPUs are sold out everywhere that there is high demand for GPUs like the RX series. I've been selling mine slowly since 2018 and it usually took 1 month to sell 1 GPU. Now you make an ad and it usually sells out in less than 24 hours. And there are less low ballers.
Back in 2018, I kept getting messages like "I know you mined with this GPU, so I will give you $20 CASH, TODAY!". While now most people send messages like "Is it still available, if so, I will pick it up ASAP". And you never get any low balls. If you list it for $100, normally you would get lowballed for $75 or $80, however you list for $100 and people pay $100, no questions asked. Meaning there is huge demand.
for 5xx series it is fine as they are cheaper. The issue is when selling Radeon VII as they are going for over $1000 on ebay. What is stopping from a buyer to pay and then chargeback. I heard that ebay always sides with buyer. I would expect a craigslist buyer to check the GPU in a system before paying over $1000