Fox is 100% correct.. when you own and pay for something you are fully responsable for its condition and therefore you work hard to take care of it, when you rent something, the popular opinion is "damn the turbulence, full speed ahead!"
Example: brand new airplane... within two weeks someone had hand written their IFR clearance on the leather upholstry because they were too lazy to return to the FBO for a sheet of paper. I have been cought in that situation once... wrote it on my brand new khaki pants. Stain defenders... washed right out ;-) didnt ruin anything or cost anyone a dime.
As for completing your own maintenance, an aircraft owner can do just about anything that he wants maintenance-wise as long as complex assembly is not required... in greater detail the FAR/AIM lists about 30 or 40 things a pilot can do to his own aircraft that many owners simply elect to hire a mechanic to do.
If an owner was to leave the annuals and avionics and major repairs of his aircraft to the mechanics and handle his own minor maintenance needs (such as those listed in the regs) the only "cost" would be blood, sweat, toil and tears which is usually a helluva lot easier to secrete than money!!! Obviously he would have to buy or borrow parts or tools which any mechanic would charge you for anyway! You would be really quite suprised to see what the federal government trusts the average joe aircraft owner to maintain on his aircraft! some of the things are simple... others you had better know what you are doing!