Sony has a bit more cash on hand than usual though. When they bought EMI for $2.3b they had like $16b. Now they have $41b. ($8b more than last quarter) If they were to make an acquisition, now would be the time. The gaming division could especially gain support for the acquisition due to MS recent moves.
A Bluepoint acquisition on the other hand would be very cheap. Insomniac is a pretty big game developer and sold for $229m (275+ employees). Bluepoint only had 90 employees, so Sony could easily buy Bluepoint and another company.
Yes, I'm not sure why people keep saying that would be expensive for Sony. They have $41 billion sitting idle and their PlayStation division is making over $20 billion in revenue a year.
A point against a massive third party acquisition is that Sony have shown an ability now to produce massive selling games and critically acclaimed new IP, from within their own studios, for a fraction of the cost. (Bluepoint has now produced 2 highly successful games back to back. I expect Sony will pick them up next for a very reasonable price.)
What would a Capcom purchase (or any big third party studio) bring to the table? A massive financial investment on a business that is valued and makes profit selling it's games across all platforms. Then limiting all these titles to one platform? It's a lot of risk.
Looking specifically at Capcom, the last time they made a new IP that scored over 90 was in 2008. They're essentially re-cycling the same legacy franchises that always appear on PlayStation anyway. You could argue it could be a preventative measure to not lose those IP, but I'd imagine Sony would be looking at how that $6-7 billion could be used carefully over time to acquire hand-picked studios, or better spent elsewhere.