#1
Hey, I'm auditioning for a band and they want me to record my vocals over their instrumental demo. How do I do this at as little cost as possible?
#2
Go to a rehearsal studio tbh. Just say you wanna record some vocals quickly for a demo, probably only charge the cost of the room for an hour + a small fee for setting up. They might even mix it in to the track for you.

It'll show some dedication to doing a good job, which any band will appreciate.

It'll cost you less to do a good job there, as opposed to doing an average job at home. Just know the songs really well, get in and bosh it in an hour.

Good luck dude!
#3
Yes, agreed. For what you'd pay for a half-way decent mic and preamp and interface, you could easily do an hour or two even in a pro studio. Assuming you are a half-way serious singer (you know... based on the fact you're auditioning for something that requires a serious demo), you should be able to go in, set up, do three takes, make a couple of minor edits, quick mix, and be gone in an hour.

CT
Could I get some more talent in the monitors, please?

I know it sounds crazy, but try to learn to inhale your voice. www.thebelcantotechnique.com

Chris is the king of relating music things to other objects in real life.