I had this happen for the monitor for my cab. The seller had great feeback, but on this dutch auction he did not follow through. I collected emails from his other auctions and that auction and got in touch with other's that had not gotten their monitor either. Emails bounced, phone calls were not answered, etc. His Ebay account was suspended, and I requested my money back through PayPal.
In that process I got his business (payment) address from another buyer who had sent a M.O., so I gave a call to the local police department and had a discussion with a detective. One thing I learned, this municipality (it was in New Jersey) would not do anything without the loss value being at least $500, this might be an issue for you. I did not have that ( I think the monitor was $150, this was a few years ago). Others that had not gotten their item forwarded me their info and we ended up having a few thousand dollars in total losses. The detective said he couldn't do too much without a sworn complaint etc., but he would stop by the address and "have a talk with them".
It worked, the very next day all of our monitors were shipped, and mine even had an extra 5 BNC to VGA cable (about $30 online).
If someone is trying to rip somebody else off, a visit by the police, or a stern letter from an attorney will usually get them motivated to do the right thing.
An interesting end note to this is PayPal also credited my money back to me, so I had the monitor and the refund. I could not resend it via PayPal since his account was frozen, so I emailed and called for about a month after that so I could get him his money that he was rightfully owed (I didn't want to stoop to his level). I never was able to get hold of him as to how I should pay for the monitor, so the monitor in my cab is still unpaid for to this day.