Ripped Off?

How come every time I take my car to get serviced, I feel like I'm getting ripped off?  Probably because I am.  My car is approaching 40,000 miles - and experience has taught me that that is when owning a car starts to get more expensive.  Sure enough, I've had to splash out on a couple of new tires recently.  And today, my car battery failed it's test so I needed to get a new one.  They also tried to get me to replace my 2 older tires, but I said no to that (if I really needed them, they would have said something at the tire shop when I got my 2 new tires).  And they also tried to get me to change my transmission fluid - but I also passed on that.  The last one is particularly galling, because this is something that the service monitor in my car will tell me when it needs replacing.  I'm already paying something of a premium by taking my car to a dealer to get serviced.  With all the new technology and electronics in cars nowadays, I feel obliged to do this rather than using an old school independent mechanic.  I guess I could save money by taking my car to get the oil changed somewhere else.  And I could probably have got the car battery somewhere else for a cheaper price as well.  But ultimately, what I really should do is get a new car.