The AGNULA project is trying to create the first computer system tailored specifically for musicians. Best of all, since it’s based around the open source Linux OS, it’s free!
Splice Music is a promising new online sequencer. It allows you to mix and match user-uploaded loops and audio files to create your own music. All the music is under the Creative Commons license which encourages musicians to remix each other’s work.
Please don’t let your financial situation stop you from writing and recording great music. Here’s a list of opensource music software for capturing and recording audio. I’ve used Audacity for a couple of projects and it works great. There’s even free MIDI sequencers in the list.
And when you’ve finished writing and recording your song, send it my way for a free and constructive review.