About a year ago, I bought expensive, used speakers through the eBay international site. The payment was with PayPal. I had communication with the seller prior to the sale. This was in the way of a cell phone call. The speakers ended up getting to me but it was certainly not as easy as buying on Amazon, or audiogon for that matter.
I did have to have a woofer replaced approximately four months later. The manufacturer told me that the speaker had been driven beyond its tolerance. I have no idea if the seller knew of such prior to the sale. If I remember correctly, he was selling it on consignment for a customer. I did not try contact him regarding such. I felt it was too late after the sale. I did not notice anything amiss on reception. But I really didn't go over it with a fine-tooth comb either. So take that for what it is worth. I paid about 50% of retail cost.
The things you will need to look out for include: an exact estimate of shipping, and how to get through customs. I was quite surprised when the shipping company called me and asked who my custom's agent was. At that point I had to do a lot of research quickly and I ended up being my own customs agent. That entailed a visit to the airport, and to customs there. Once customs had released the speakers, the shipping company was able to bring them to my home. You will also need to verify if any tax will be added (vats). As I understand, this can be hit or miss.
All in all would I do it again? I probably would. I really wanted these speakers, and they weren't available in the United States at the time. But it can be somewhat of a hassle.