" . . . to possessing the 'idea' behind the piece?"
The Financial Times on the market for performance art. Tino Sehgal gets a mention:
"Berlin-based artist Tino Sehgal has evidently turned collecting criteria on their heads. He sells his performance art pieces by means of verbal transactions in the presence of a lawyer with no written contract. Instructions on how to re-enact his works are delivered literally by word-of-mouth, with collectors under strict orders never to photograph or video his 'constructed situations'. Yet they sell in editions of four to six for $85,000 to $145,000 each, according to The Art Newspaper."