Obviously, a demo service has, or should have, a studio - but that's not the point. To have professional musicians record your song properly is something completely different from having some BIAB-Backing track put behind your lyrics and some semi-professional singer improvise a tune on top of them. By the way, you would not get musicians plus the studio and engineering time for $85. $1.000 and more would sound more like it.
Sometimes it helps to read the context before answering ;-)
I'm a lyricist, not a poet, by the way, although there are about 150 lyrics out of 400 that have not been set to music yet (so they are not songs, neither poetry - hence "... at best"). I'm not a pro, but rather productive, writing for several live bands and the odd solo musician.
I've also written for a producer who produces demos for singers in Germany. Depending on what they contribute themselves - from nothing through complete songs that just are not properly produced - he actually may compose melodies for them, or even write the whole song (where I sometimes contribute the lyrics). His service is semi-professional, and he does not master the songs - although to my ears his productions sound very professional. He charges between 300 and 800 Euros, which I would consider a true bargain. These songs serve to present the singers. They are not meant to be pitched - although obviously none of the people involved would mind if one or the other was picked.
As far as I could make out, Anne writes lyrics that she calls songs (you might check out her other posts).
Cheers,
Bernd