have a look at this:
http://www.ebay.de/itm/Liegerad-mit-Elektro-Antrieb-Sinclair-C5-wie-neu-Museumszustand-/291329025975?ssPageName=ADME:SS:SS:DE:1120

A C5 in ebay.de, listed as "as new, in museum condition", buy now price £2,000.[woot] [woot]
No Serial number, and not 100% complete.

Atleast it's not that far lol

Yet another dreamer, looks like the first guy has started a ball rolling. This guy is also asking for around £2,000. At least this one IS new, original, and was boxed.

http://www.ebay.de/itm/Liegerad-mit-E-Motor-Sinclair-C5-NEU-unbenutzt-Museumzustand-/181626289655?pt=Sport_Radsport_Fahrrad_Kindersitze&hash=item2a49c53df7

So the dreamer in post #1 came down with a bit of a bump.

His buy now price for a bog standard single battery model, no serial number and a few parts missing, but in good condition, was £2,000. It didn't sell, so he reinserted his add with no limit. It went for £857 this evening.

This makes me very happy, but that's another story, I'll explain at a later date.

Yet another Dreamer.

http://www.ebay.de/itm/CTS-Fun-und-Elektrofahrzeuge-Hannover-Sinclair-C-Bj-1985-/251810309955?pt=Hilfsmittel_f%C3%BCr_Gehbehinderte&hash=item3aa1106743http://

C5 in tatty condition, looks like the [color=red]pedal[/color] shaft has been cut through, but his asking price is quite reasonable, £2,500.

[color=red]Edit: Spelling mistake.[/color]

http://www.ebay.co.uk/itm/Sinclair-C5-electric-trike-/111589033691?pt=UK_Car_Parts_Vehicles_Automobila_ET&hash=item19fb3986db

A bit more like it...

Trouble is here in Germany C5s are few and far between, someone sees this offer, thinks OMG I've got one I'm not using, and jumps on the bandwaggon. It happen not so long ago, see above.

jockywilson11's example looks like it's worth it.