My acquisition of 4 sealed Rahaga and a Fikou polybag this year, whom were missing from my collection, is the only one I have that would count. Someone posted all six Rahaga, the Fikou and a Visorak (Vohtarak I believe) in sealed condition on an auction website some time ago. I hit the auctions for the four Rahaga I was missing (Pouks, Kualus, Gaaki, Bomonga) and the Fikou. The price was dirt cheap, under 1000 Ft (our local currency) since the guy probably didn't know the worth of discontinued sealed sets. So, a bidding war ensued among the others while I sat patiently, waiting to snipe in the last 10-5 seconds. I won Pouks and Kulaus, but someone else sniped the other three sets.
Now, the site does not have any kind of messaging system, and the seller was the only person I could contact. As such, I asked him to relay a message to whoever won those three to get into contact with me so we can work out a deal. I had little faith that it would work, because obviously someone sniping sealed Bionicle sets has to be a collector like me, right?
Luckily, the person contacted me, and I proposed either a trade for much larger used Bionicle sets I own duplicates of (I specifically offered 2004 titans) or to buy them from them. At first the person seemed open, but then I got a reply that was even more dreadful than a straight rejection.
Turns out the buyer was a non-collector parent of kids who aren't even fans of Bionicle, she just wanted to get the kids some cheap Easter presents. To my offer of trading larger sets, she said "there is no point in giving them bigger toys, because they destroy everything anyway" and that the Rahaga and Fikou "won't last a month either".
Until now I was just eager to get sets for my collection, but now the stakes were high. I had to save these guys from the little monsters. This is Bionicle history we're talking about, sets that remained sealed since 2003 and 2005. I'm not going to let that be destroyed.
So after an enthusiastic e-mail detailing the worth of these sealed sets in this condition, we finally settled. I ended up paying a whole lot more for these than I did for the ones I won on the auction, but it was very, very worth it.
Not only were they elusive sets that I acquired, but I saved them too!