Semi off topic, yet strangely important!

[Yuhaney]

You can BUY the whole soundtrack on CD if you like.

And music is composed by Mikko Tarmia.

And about Collector's Edition, there is already that one.
It includes all the 3 games with latest patches. Just Google Penumbra Collection and find the shop nearest to you.
...or if you like, you can buy the collection straight to your hard drive, if you like.