Zelle is a bank wire, essentially. There is no recourse or charge-backs by the buyer. It's the only 100% safe electronic payment I know of, (for the seller).
Venmo, Paypal, and the like are backed by a credit card to which the buyer could contact and file a claim/ dispute resulting in the seller losing out.
The other option would be to contact TMRAudio.com and see what they would offer for your speakers. I've heard nothing but good things about them.