Hey Noob -
I'm with you on getting a demo done - my voice is so-o, and sounding professional is important when submitting songs for consideration.
I'm a TAXI member and use a service out of Nashville (Kim Copeland Productions) that has a nice arrangement - songwriter demo session that allow for a reduced rate. Not sure of the type of music you write, but if you're looking for someone that can produce something that sounds professional for submission to a place like TAXI, it's a good option.
I've worked with Kim Copeland for a few years. I do everything via email and phone. I leverage her songwriter demo group day session. Several songwriters book into a single day, allowing her to give what I think is a great rate as well as input into the song production as the songwriter. You can check out the demos I've done with her on my web site lyrist101.blogspot.com.
Rate for these was $895 which is fairly standard for the quality level. She'll also do a song critique for $40 that comes off the $895 if you demo the song. Rates are subject to change, so contact her for specifics (depends on group day, usage rights, etc.)
Beard Music out of Nashville is also good with multiple genres and works via email. I've never used them personally, but several in local songwriting groups have. Rates are slightly higher than Copeland's and slightly less personal interaction, so not really for me, but always someone to check out.
Hope this helps a bit.
LAS