The rumor that the budget doubled to $60 million came from Surfer Girl. Since when do we trust Surfer Girl?
In the same rumor, she claimed that the game was struggling in development, and would ultimately be "barely mediocre". She also claimed that the team had a high turnover rate, yet over 90% of the team that worked on the original Killzone are still at Guerrilla.
She also claimed that it would dethrone Shenmue as the most expensive game ever made ($70 million), despite the fact that GTAIV was already approaching $100 million when the rumor was made.
She clearly didn't, and has never known was she's talking about. If it's even a she...
Here's the link:
http://ps3.qj.net/Rumor-Killzone-2-budget-doubled-because-of-Guerrilla-Games-/pg/49/aid/112518
It's been said that MGS4 cost a bit over $50 million to make, and given the size of Kojima Productions vs Guerrilla Games, and given the wage disparity between those in Amsterdam and those in Japan, it's likely that the game probably cost a bit less than MGS4. Developers in Amsterdam are generally paid half of what they are in NA, for example. Also, much of Guerrilla's costs centered on team expansion. They had to purchase a rather hefty generator to supply their facility with enough power to work on Killzone 2, for eample. These changes were necessary, and were an investment in all of Guerrilla's future projects, and not just Killzone 2.
Going by that, it would have to sell ~1.25 million to break even.
Even if the game cost more than that, as Benga surmises, it would still take less than 2 million to break even. It should easily clear that mark. Hell, look at how fast LBP crossed 2 million. This is the only ps3 game with more hype than LBP, and it's a better fit for most ps3 owners than LBP, so it should outsell LBP.
Edit:
And it looks like Surfer Girl used the wrong figures! Killzone 2 didn't cost 21 million Euros. It was 16 million Euros, which was 21 million USD at the time:
From GameSpot:
While Black Book cost more than 16 million euros (approximately $21 million)
So even if SG's 2x figure was correct, it'd only be $42 million.