If you're using Growl 1.3.2, to enable a sound alert--
Launch Growl, Applications Pane, highlight the eBay app, select Configure (at the bottom of the window), then click on the Notifications Tab, and there you will find a drop down menu to play notification sounds.
At least I think that is how it would be done, presuming there is an eBay hook to Growl. Alas, I know nada about eBay.
27" i7 iMac (10.13.6), iPhone Xs Max (12.1)
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