Mozilla has been paying the main Firebug developer for a long time to work on it, but I've never heard of an open source project that would like to be "acquired", whatever that means. If hiring all of the project's developers is what you mean, quite a few of them had high profile jobs already, so funding wasn't an issue here. As for the reasons why simply incorporating Firebug into Firefox wasn't a viable solution, see the original post.
