Assuming it's the same concertina, it went for USD$7700! It's not bad at all for an older model, some people still have money 
The winning bidder has apparently pulled out of the sale and I being 2nd highest has been sent a second chance offer. I'm not sure what to do now....I'm in the uk and the seller is in USA and there seems so many scams these days how can I be certain it's a genuine offer and not some scammer. The seller says he wants to proceed through eBay channels but has indicated on the listing he dosnt want to use paypal .........what do I do?..
Good notion to question and verify. I had a similar experience on a concertina eBay bid a few years ago, with about $6,000 at risk. The "second chance" offer looked very legit, but I knew how to contact the seller outside of eBay and discovered the "second chance" was a scam.
Going through concertina.net is a good route for you to verify this offer. Regarding the concertina you bid on, I live in Washington state and met with the owner a few months ago. I've exchanged a few emails with him, so have a way to contact him. I'd have confidence working through the concertina.net message route, but if you have trouble getting in contact with him, let me know and I can send an email on your behalf requesting verification.