user35760: Relying only on publicly disclosed data, what is the most expensive Bitcoin purchase that has ever occurred?
"Expensive" can be determined either by:

Highest purchase price in Bitcoins
Highest fiat value equivalent at the time


user36278: If you mean the greatest amount of bitcoin spent,  the "bitcoin pizza" comes to mind. At a whopping 10k BTC spent.
Pizza for bitcoins? (bitcointalk.org)

user35777: I'd say it was the selling of dice gamling site SatoshiDice in 2013, according to the former owner it was sold for 126,315 BTC which was equivalent to ~$11,5 Million at that time.
More details can be found here: 
https://bitcointalk.org/index.php?topic=101902.msg2751536#msg2751536

35760: <p>Relying only on publicly disclosed data, what is the most expensive Bitcoin purchase that has ever occurred?</p>

<p>"Expensive" can be determined either by:</p>

<ol>
<li>Highest purchase price in Bitcoins</li>
<li>Highest fiat value equivalent at the time</li>
</ol>
 36278: <p>If you mean the greatest amount of bitcoin spent,  the "bitcoin pizza" comes to mind. At a whopping 10k BTC spent.</p>

<p><a href="https://bitcointalk.org/index.php?topic=137.0" rel="nofollow">Pizza for bitcoins? (bitcointalk.org)</a></p>
 35777: <p>I'd say it was the selling of dice gamling site SatoshiDice in 2013, according to the former owner it was sold for 126,315 BTC which was equivalent to ~$11,5 Million at that time.</p>

<p>More details can be found here: 
<a href="https://bitcointalk.org/index.php?topic=101902.msg2751536#msg2751536" rel="nofollow">https://bitcointalk.org/index.php?topic=101902.msg2751536#msg2751536</a></p>
