Can Audiogon help in any way, or is the method of payment used outside Audiogon's parameters.
I had my first sale last week with interconnects, Audiogon held the payment until the cables were received, the website states it can take up to 8 days for payment to clear. I used The credit card payment system, fair for all parties.
I would fly before parting with 15k.
I flew a few hours last year to see a pair of speakers. Emails led to phone calls and then meeting in person, worked well.
I emailed Audiogon last year to verifying a vendor in Turkey. I wanted to know if I could trust the seller information. I got a prompt response, they looked into the vendor and said everything was in order.
No harm forwarding the police in the Netherlands all relevant information on this vendor.
Good luck.