While it's tempting to pick the Paladin from Sunday, I'm gonna go ahead and go with this:
As of right now, this is the week's most expensive kill in New Eden, at a little over 24 billion ISK. The real question, though: at what point -- if ever -- does a PvP ship finish paying for itself?
EVE is full to bursting with pilots that pride themselves on their kill/death ratios. It's probably the second biggest e-peen in the PvP'ers arsenal, after total ISK damage inflicted. A lot of guys aren't quite that prideful about it, but still use it to measure their success or failure as an EVE PvP'er. And of course, it's pretty easy to inflate the statistic by running in larger gangs, or engaging in relatively low-risk POS warfare. Still, get into PvP enough times and you're going to lose your ship. Get into PvP enough times with the same ship, and it's going to explode.
I've already spoken of the dangers of being too predictable, and indeed, that's how this Nyx fell. He'd been spending the last week or so in G-ME2K, hot-dropping and popping AAA mission-runners. He'd killed seven ships so far this week. But he got a little bit greedy, a little bit over-confident, and used the same scanner alt/tackler pair one too many times. He fell on a mission-running Tengu that was either bait, or close enough to some tacklers that it would serve as bait. Eleven minutes later, his Nyx was dead and he was podded. Losing a long-serving ship happens to the best of us.
But the key phrase here is "long-serving." In 2011 alone, this Nyx had 470 kills totalling nearly 400 billion ISK. Only about 65 of them are structure kills, and five of those kills were Titans.
Yeah, this particular Nyx was lost but I'd say the pilot got full value out of her.