A supposed prototype iPhone 4 has appeared on eBay.

The device is described as a prototype/tester unit, “one of a VERY small amount of Apple prototype devices and never seen on ebay”.

The prototype phone is running Apple's software testing suite, SwitchBoard.

It has a prototype logo on the back.

The prototype is fully functional, according to the eBay post.

The auction will run until 26 August and the current bid (on Wednesday lunch time) is $4,500 although the seller says that he will sell it now for $10,000.

Sales are to the US only.

The seller, ddnets, appears to have a Top Rated Seller rating, although the majority of reviews are from sellers rather than buyers. Other goods on offer include various broken iPods and old iPhones.

The seller, Sonny Dickson has posted a video, which can be seen via 9to5Mac.

In 2010 Gizmodo published photographs and analysis of an iPhone 4 prototype that they had bought for $5,000 after it was left in a bar. Apple sued the blog over the incident. 

Follow Karen Haslam on Twitter / Follow MacworldUK on Twitter 

Related:

Sale of iPhone 4 prototype - two charged

Lawyer confirms identity of 'lost' iPhone seller

iPhone prototype: web reacts to raid on editor's house

Criminal charges possible in case of prototype iPhone leak

Calif. police seize computers in 'lost' iPhone case

Report: US police investigate 'lost' Apple iPhone caper

Apple demands iPhone prototype back from tech site

Gizmodo paid $5K for next-gen Apple iPhone 4G