Color had 41M in funding, of which $25M are left. That money goes back to investors. Apple threw in maybe $5M. That also goes to investors.
Apple interviews each employee and decides who stays and who goes. The value for Apple is that a team that works together well is more than the sum of the parts, but only if they keep the people who would fit well within Apple.
The people who stay usually receive a retention package which could be a mix of restricted stock units and cash, vests over three or four years, and is determined by:
- the experience and seniority of each person.
- the perceived value of each person to Apple.
Apple tries to gauge what it would take for the core of the team to stay long enough. Someone may need 500k over four years in addition to salary, someone else may need 2M. It's impossible to say what is being offered to each developer unless you're an insider.
For that reason nobody can know what the deal really costs to Apple, but it's definitely more than what investors get. Otherwise, the really valuable people would not go to Apple just for a paycheck.
Source: I've been involved in deals of this sort since the late 90s, mostly on the side of the acquirer.