Even the studio in my article about building one cost a few hundred dollars at minimum. If the words "a few hundred dollars" make you run for your food stamps, you might need to start with something a little cheaper, like perhaps in the no dollar range. I've listed three options that I've found on the internet over the years, and each one is for a different kind of musician or composer. If you're like me and you're a little bit of all three types, then try all of them:
For those who play an instrument or have a band and want to record it:
Kristal Audio Engine
This could be Window's answer to the Mac's GarageBand. You get 16 tracks and a professional-grade interface. This is a great way to get yourself acquainted with multitrack software.
For you electronic/software nerds:
They call it 'the first free soft-studio'. The idea is that it's an entire studio's worth of gear running on your computer. It has low system requirements and it's fun to use once you get the hang of it. Note that there's quite a learning curve to get past, and your music is strictly electronic-based. If that's what you're going for and you have some patience then this is for you.
For you of the ruffled shirt, powdered wig and real music training:
If you know how to write music on a staff and enjoy doing so, then this is perfect. It's so easy to use that a one-armed dyslexic monkey could do it. You select your time- and key-signatures when you start a new piece and then it automatically calculates the structure of each measure for you as you place notes. Without ever using it before, I was able to fire it up and transcribe 8 measures of a piano song I've been working on in about 15 minutes.
I was just kidding about the ruffled shirt and powdered wig thing. Although if you do wear these items, please send me a picture.