Caveats

 When buying something online, specifically used things, be careful.

People make mistakes or are criminal in intent. Make sure to know as much about the thing you're buying as possible. Read online user/owner manuals.

Make sure the item is returnable for a reasonable fee.

Make sure eBay is guaranteeing the item.

Check the web for prices, including other sell sites like etsy, etc.. There are frequently cheaper prices elsewhere, and even retail may be cheaper.

Is there sufficient data from the seller? Images? If not, contact the seller. Be polite but insistent. If the seller is not forthcoming, consider moving on. A similar or better deal may occur after a time.