Hello there
Certainly having your characters animated via live2D or whatever can add a lot to how much you'll be spending in art, it can make your project way eyecatchier.
For example, consider checking these visual novels, they use live2D in sightly different ways.
Maitetsu
https://www.youtube.com/watch?v=DmBAGmUMAks
Crystalinne
https://www.youtube.com/watch?v=ggHFtWDQsVM
Nekopara (doesnt use live2D, but E-mote which is pretty similar)
https://www.youtube.com/watch?v=VcgvNZXoU2E
Animating the characters doesnt really take that much time, as I see it the issue can be with two things:
1. The engine you'll be using to make your visual novel, it might not be as straightforward to use it with live2D, so you or your programmer might need to take a good look at it.
2. The preparation for the characters to be animated, when drawing the characters you'll need to take an unconventional approach, that meaning not giving the animator a flat image, but instead having the illustrator draw the characters with every part in a separate layer, for example: fronthair, right hair, left hair, back hair, eyewhite, pupil, etc each one on a separate layer.
And this might take some time, and probably the artist will charge you more for drawing this way.
Either way, this can be only one of many parts on your project that can help it stand out, a lot of the cost in money and time can vary a lot depending on how you want to implement live2D on your visualnovel, it might be slight movements for the sprites, or only for the CGs (money shots), or animate everything, but as you know, you can reuse a lot of the assets throughout a visual novel, and many doesnt even have that many characters.
Also check the Neptunia games, the main characters are animated, but a lot of the secondary ones are just static sprites.