I base my quotes on sqm and tile size,the smaller the tiles the price goes up.If its a small area with lots of cuts say a wc floor then I may double it due to the work involved.
http://www.youtube.com/watch?v=eEibyAJVLr0
I tiled this area a few weeks ago and it took a day all tiled and grouted due to lots of cuts around the doorways and the centre piece.
Price charged £150,that included adhesive (about £8 )