A little story about my instructor,
I remember when I first got into this great hobbie, I had a hard time finding someone to teach me to fly.
Well when I did find someone to teach me I spent about 2 days and about 4 flights before I soloed. My instructor was a great teacher!!
Any way to make a long story short I offered to by him some fuel for his time but he told me no it was his pleasure and not to worry about it. I remember that he was more excited about me soloing than I was lol... (he was jumping and yelling like a kid) that I soloed!
anyway the next weekend when I came to the field for my first flight without my instructor at my side, he was at the field and before I had a chance to get everything unloaded from the car he called me over and said that he had something for me. Hummm... I said to myself. He told me to wait a min. then he walked over to his van and pulled out a box and brought it over to me and said here I got you something. It was another kit!!! he told me that he bought me a gift for soloing and that this would be a good second plain for when I was ready to move up from my trainer.

the morial of the story is that alot of instructors (I believe) get more joy out of there students soloing than anything that we can offer them.
I tell you that when I get to the point to start to train students I will most likely do the same as my intructor had done for me and I will NEVER take any money and ect.. and most likely buy my students a little gift to get them off on the right foot in this wonderful hobby!!!!