If you already are doing her LAQing then you should already have a pretty good idea as to how her piecework is. IOW poorly cut pieces would show in the final flimsy.
Already doing her LAQing does not mean you should feel obligated to help her out. Your "business" is LAQing. If you agree to this piecing, are you opening yourself up to others wanting you to do the same for them? Or is she apt to rely on you in the future, more than you want?
Price? While hourly pay is usually different than LAQ fees, you probably know what you figure you make per hour. Maybe go with the same hourly rate?