Lead sheets are what the publisher does and is his responsibility..
the publisher supplies the lead sheet, if the producer recording the song requires one.
The publisher needs to control who does the lead sheet to make sure it is a true rendition on paper, of the song,this is a copyright issue.

A real publisher will not charge you up front for the lead sheet...But it will be charged back against you, just like the cost of your demos are when the bucks come rolling in.

Doing demos of a song that I published we never did lead sheets . But we did the songs by the numbers..

At the point the song was going to recoreded is when the lead sheet was done..

Thsi is pretty much industry wide ...

I would be very suspect of any publisher who wants you to do the lead sheet, and then suggests so and so to do it.
The publisher doesnt need a lead sheet to 'pitch" the song.

Dude