Do all these scam buyers have 0 or very low feedback (less than say 5)? If so, if you set your buyer requirement blocks, it should hopefully stop them. if they have phone verified their account or have opened a PayPal account it won't stop them, but still worth a try. 

Click on this link to set blocks. Set the others up while you're there, like blocking people with more than 2 unpaid item strikes in 12 months.  http://offer.ebay.com.au/ws/eBayISAPI.dll?BuyerBlockPreferences

As the camera sold for a large amount, you will be paying a LOT of fees on that if the buyer doesn't pay. On the 15th May, open up an unpaid item dispute, then go back exactly 4 days later (to the time, not the date, so if you open the dispute on the 15th at 8.02pm, the earliest you can close it is 8.02pm on the 19th), and close it. That will get you the fees back that you paid on the item.

If you're not sure how to open a dispute, go to the item on your selling page and click the down arrow at the right. Then select "resolve a problem". On the next screen, select "I sold an item and haven't been paid" and submit. The next page will ask you to confirm. The dispute is now open and the buyer has 4 days to pay.

If they don't, go back to the dropdown next to the listing and select "close case". The next screen will take you to the resolution centre and the dispute will be towards the bottom. On the right, click the dropdown and select the option to get your fees back (can't remember exactly what it's called, but you'll know it when you see it). 

On the next screen, select no (the buyer hasn't paid) and then close case. If the option to select no is greyed out, check the top of the page as it will tell you the earliest you can close the dispute. Go back then and close it. 

Do this for any other scammers that try to pull that stunt. You get your fees back, they get a strike against their account.