[AGS] THE LAMENT OF FINDING AN ARTIST

As I sit here with my project, the writing coming along nicely and the concept all fine and dandy and even programming covered I find myself turning to these forums to get some input and advice.

Long story short, and to keep most of my concept to myself, I am going to turn one of my novels into a game with the Adventure Game Studio engine.
I pitched the concept to a friend who has programmed in this engine before and they were all aboard along with two others, my partner who designed the original characters and their sibling who is a talented artist.
So the line-up starts good, I'm an author and have written for game and stage play before so I hold that responsibility while my partner and my other friend oversees the entire project and programming with the sister working on the art.

Now there is only one huge flaw in this and this is where I find myself in the never ending cycle of frustration.
The sister never works.
We agreed that if we were knee deep in school work or occupied with our steady jobs then we were not obligated to do anything with the game, our basic income comes first after all.
But it has now been weeks without anything where I have asked the sister to do one mock up shoot of how we want the game to look so we can see if the art design we chose will work for the atmosphere we wish to convey or if we have to change it all together.
And nothing.
Over one month of me asking her and more or less pushing her and she has delivered nothing.

Now the trouble is this, if she had told me she was not interested or felt this was out of her league, I accept that, I would move on and try to find other means.
But she keeps insisting she's interested though the interest certainly is not showing.

And so I find myself in this predicament.
The idea is solid, the story is good and over all if I can hook a good artist, this can actually be something I would be more than proud of.
I'm not aiming to become the next big thing but there are a lot of personal reasons to get this game done and out there.
However I am not a wealthy person and I also have the moral that an artist should not have to work for free.
Of course the first thing coming to mind would be "why not start a crowdfunding" or "a kick starter!".
I won't do neither of those until I have a project that would be worth that or be further into development.

So what I ask is some advice.
I really wish to get in contact with artists but I have no idea how to come to an agreement or even where to look? I do not wish to exploit someone's hard work after all.
As for the sister situation I have no idea how to approach it, I guess I'm wondering if I should keep beating a dead horse or if I should just pull the plug and try to look elsewhere?

Any advice is highly appreciated.