I think the seller has re-listed this at a lower price once already as, from memory, it was nearer the $2k mark previously.
Trying to make sense of Ebay pricing, I can see a modded 1969 EB-1 from Japan at the moment for £4,344.70. This has a bridge pickup and a third knob rather ungracefully grafted in. There are cleaner examples, also in Japan for £5,233.24 and £4,520.87 (no pickguard but a stand). There is one 1968/69 in the US for £3,060.13 with OHSC.
I was in London last week, and one shop was selling a Kalamazoo KB for North of £600 ($788.18 as of just now). The price is also slowly increasing on even the crappiest of Japcrap instruments.