Does anyone have reccomendations for cost-effective software for Macs? I have looked into the Pro-Tools package, but it's about $1,000 for everything. I would like something that allows me to plug in guitars and mics for vocals, and something that has a drum-machine capability.

Any ideas?

Pro Tools has a free version that doesn't rely on specific hardware. The only set back is that it's 8 tracks only but it may be worth checking out to see if it's worth upgrading to the $1000 solution. Actually you can get the Digi 001 for about $700 now.