Hi Matt,
I'm going to disagree with Skippy and the others (all of whom are my betters as far as knowledge about recording goes) for the simple reason that I don't think you have any idea what you're getting into, and I mean that only in the kindest, best way.
Personally, I think you'd be far better off finding a local amateur or semi-professional recordist who'd be willing to help you do your demos, whether inexpensively, out of friendship and interest in the hobby, or in exchange for use of your voice on a couple of his projects. I traded some voice-over work for recording favors in decades past, and it was a good deal for all parties. Some people simply should not try to own the means of production. You may be one of them. Plus, it's kind of fun (and shocking at first) to hear your voice being used on local radio and television commercials.
And even if you DO want to own some recording equipment (why, oh why?), I'd still steer you toward cassette tape and/or minidisc rather than the fancy stuff. Here's why:
Your voice has got to be great, and at the top of your range, your projection will overload a lot of systems, yet compression on operatic vocals (or pitch correction or reverb or all the other processing that goes into producing pop vocals, for instance) is ENTIRELY inappropriate for an operatic audition tape (or CD). If I was listening to your tape and it sounded commercially processed, I wouldn't even finish it -- I'm auditioning a singer, not a record producer.
Just getting a CD from a singer would make me suspicious. I'd much rather hear a well-recorded cassette of a live performance, with accompaniment. I KNOW what that's supposed to sound like, and my hearing can adjust for the limitations of the medium.
Just the MICROPHONE for a voice like yours should not cost less than about $700, and it should be backed up by a microphone preamp in the $1800 to $2000 range. Those are minimums -- you'd probably benefit from MUCH more expensive equipment (like $5,000+ mics and $7,000 mic preamps). All this before it ever reaches any sort of recording or mastering unit. You're kidding yourself if you think you're going to make a great recording of your voice with $1,000 in new equipment.
A good cassette deck for $400 is the Tascam 202 Mk III, available from Zzounds.com. It has mic inputs on the front -- not great, but useable. It has two *recording* wells (not one recording well and one playback-only well). It makes great dubs. It has auto-reverse. It's cheap and reliable.
A good mixer with 4 mic preamps and phantom power is
the Mackie 1202 VLZ PRO, available used on ebay for about $275. Note that the 1202 and
the 1202 VLZ are not the same as the latest 1202 VLZ PRO -- they should be cheaper, but you'll want the VLZ preamps.
Good mic cables are about $50 each -- BLUE Kiwi are great, available from Music123.com.
The Mackie lets you record in monoaural and output to two channels (this means the sound on playback from your Tascam won't just be coming from one speaker, but it's not true stereo -- you don't really need it).
A minimal mic for your voice would be
the Studio Projects C-3; don't bother with the C-1 for your voice. The C-3 is $350, multiple pattern (which lets you add in some natural ambience), and is a stone bargain at the price.
So here's a sample list:
Tascam 202 Mk III from ZZounds.com $389
Mic Stand and
BLUE Kiwi from Music 123 $90
Used Mackie 1202VLZ PRO from ebay $287 (shipping)
Studio Projects C-3, new, ebay $349
Blank cassette tapes $20
That's $1135 without even getting into a CDR deck or minidisc player or sound card or any of that other stuff.
I don't mean to be a Luddite or a curmudgeon, but I've worked with enough good voices to know that your gifts may not be in electronics, nor should they be.
I sincerely encourage you to network/locate/find/beg-borrow-steal access to a recordist who might be willing to work with you for free or trade in lieu of spending a bunch on your own recording equipment.
My apologies if this seems presumptuous or contrary. Although I acknowledge the validity of what everyone else here has said, your situation may warrant a simpler approach.
With kind regards and hoping to hear you sing live some day,
Mark H.