Have I been conned on ebay

Have you tried contacting the buyer? If not, try that before using the dispute process. If it was an auction-style listing (rather than 'Buy It Now'), it's possible that the buyer bid at an early stage and hasn't been able to pay yet. Their feedback would be a good guide here.

Either way, don't be too disheartened by this experience, as eBay can be great when it works, which (in my expereince) it does in the great majority of cases.

I ended up opening an unpaid item case at the Resolution Centre which I closed after 4 days and it was recorded on the buyer's account.

The buyer got in touch today and explained that he was abroad and that because of the unpaid item strike, he was unable to complete the payment through paypal. I've emailed the Customer Services department explaining the situation.

Have you ever got in touch with them before? just wondering how long it takes for them to reply and what the likely response might be...I'm guessing they will remove his unpaid item strike and the transaction can progress as normal? He's started emailing me now though saying he will send a cheque instead but isn't that going outside of E-bay rules?

I have had reason to contact eBay customer services previously, about a year ago now, and so far as I can remember they replied to emails within 1-2 days, which is pretty standard for most businesses.

I'd remain wary of taking payment by cheque, and you're right that in general cheque payment is not acceptable on eBay (except for a few item types - see here). If you can take an alternative form of payment, I'd suggest that you do. Whatever happens, don't ask for the unpaid item strike to be removed until you've received cleared payment.