If you start at $100,000 per art piece, and keep doubling the price, it is possible to reach $51,200,000 in just ten iterations.
For discussion purposes, we are strictly following the numbers. Remember that you only need to satisfy the 9th step, which is $25,600,000. As soon as the artist announces that the current asking price is $51,200,000, the street value becomes $51,200,000. The graph shows a total of 1,600 works, but you only need to sell 1440. Announcing that the 1441st work is at $51,200,000 makes that price the street value of all othe other art pieces.