Dilema

[Sand Dancin Donkey Walker]

A golden rule for myself is 'never spend more on eBay than you can afford to loose'
Though I would personally drive to check them out and pay cash, which is a better safe option.
Pay a small as you can get away with deposit, then travel.

[Pharos]

This is a tough position, and I am in similar, but for £10.9k and German Ebay ad.

My credit card is nowhere near enough although it is dedicated to Ebay and Paypal, and so has three levels of recovery.

I know that I would want mine but am getting no response from the seller, and the only way I would do it is as above, hire a van, go with a friend for a second opinion, and checkout the speakers and also, and more so, the social signals of the seller.

[montesquieu]

From a quick side conversation with Adey, the speakers are over 2000km away, so travel isn't really a sensible option.

My advice is find a pair either nearer hand or from a trusted source.