Cannot see anyone in the UK paying £500 for a black box. Probably struggle for £300. So it was more than likely to go abroad. The British market is, as it often has done before, lagging behind the values elsewhere for many classics. Funnily enough I have a few black boxes to restore. A discussion with buds asked what I would be asking. £500 bottom value, was the answer. They refused to believe that was achievable. My answer, they are not making anymore and it has to be worth my paid time invested in doing the job. So I was bang on. And before we get into, is it worth it?. I would remind you value and worth are two different quantities. My answer to that is if I did not have a complete car and some bits I would not be looking at doing a Messerschmitt at those prices, and I love the cars. I would be tackling something less valuable. So no different to many a Brit there then, bye bye 'Schmitting as a hobby.
As a dealer you do get shafted by a deal such as above, actually. The buyers in America would clearly have paid more but had to allow for the expensive postage. Probably a loss of £50 or so to a result selling it in America direct. That potential margin has gone in shipping costs.
Then ask how much of the shipping cost over a few years is down to tax hikes and State trade barriers in additional paperwork. There you have a real estimate of currency adjusted index linked inflation which is running at over 7% and who is mainly responsible. Forget the Local inflation rate on a special Government box of goods selected to keep you happy and pay claimants less money next year in last months figures (hurrah a bit). That 7% is why trade has become difficult, as much of this is on transportation. The answer is clear for Governments, STOP WASTING MONEY. That % is perhaps also the rate we are loosing living standard flushing our future into unproductivity!