Most of the good luthiers have all their guitars pre-order by clients. So when you visit a workshop, you may see nothing or a work in progress guitar.
Just my two cents.
I'm sure this has been your experience but by in large this is not the norm. I can honestly say that I have never visited a fellow luthier that doesn't have at least one instrument, especially ones that play as well, around for their visiting prospective clients, friends and themselves to play.
I totally agree with Marcus in that you should visit the shops of the luthiers of your choice. If nothing else it's an opportunity to get acquainted with the luthier and him/her with you so that if/when the day comes that you order an instrument there is a connection beyond email or telephone.
I always have a few instruments around for prospective clients to try before placing an order, myself to play and occassionally to sell if I have had the time to make new ones for the stable or more likely, the significant other decides it's time to de-clutter the living room (I'm speaking from personal experience here as I've just recently been informed that "Some of these have to go!"
). You might get a good deal by walking in and visiting your favorite luthier.