I've bought all my speakers used. Shipping just gets expensive and being able to listen to them and evaluate their condition is crucial. Once you narrow down what you are looking for I would search locally on FB marketplace, Audiogon, US Audio Mart and used hifi dealers or maybe even Craigslist. Take your time finding what you want. The last set of speakers I bought used were 3k less than current retail and only 2 years old. I drove 2.5 hours each way to demo and then buy. I recently bought a sub and saved over $ 700 vs new and that included shipping. Both in excellent condition. Well worth the savings to me.
Definitely talk to the seller by phone if you can. Research their location and if not comfortable arrange a public meet up or wait for something else. I have found most people selling high end gear are great to work with and can provide valuable insight as well.