Wow, this topic draws an amazing amount of hate.
As far as i see it, Sebastians options are rather limited, if he can't pay german tax.
1. He could decline the prize.
2. Keysight could deliver locally
3. Keysight might swap it to cheaper scope and he pay tax for that one.
True, but instead of discussing his options with Keysight, getting clued up about the facts or simply declining the scope he decided to publicly attack Keysight instead
Selling is not really an option.
If he isn't a company he can't write a tax invoice. No company would buy his scope under this condition.
That's not true, I've myself sold quite a few very high priced technical items to businesses. If the price is attractive they don't really care about VAT, all what matters is the bottom line.
A private buyer is rather improbable. Keep in mind Germany does't really have a great private market for high prized scopes.
If he sells internationally he would get into tax-hell part two, now from the other side.
No, he wouldn't. Import taxes are the buyer's problem. If he sells to someone say the US then the buyer is responsible for paying customs and sales tax (where applicable).
In addition, he could easily sell EU wide.
In both cases he would have to pay additionally income tax for selling the scope.
Not necessarily, it depends on his overall tax circumstances. Any competent Steuerberater will gladly tell him how much he would have to pay.
If he registers a company for selling the scope he gets stuck with eu warranty law and ultimativly some form of tax again, for selling the scope.
There's no EU warranty law. There are EU regulations that member nations have to convert into national laws. I know that this particular point seems to be hard to get for many Germans, which is the reason why German ebay is full of silly disclaimers stating that EU law mandates they provide some warranty (and no, 'Gewaehrleistung' is not the same as 'Garantie').
As a company, distance selling (right to return) and Gewaehrleistung aren't an issue if you sell to another business, it's only an issue if you sell to a consumer (private buyer). But registering a company just for selling a scope would be silly.