How do you bury a pet?

Another pet bit the dust yesterday.  That's 5 in the last year!  Three dogs and two cats have died, all of them older.  They are all buried in my yard.  (Many cities/towns, etc. do not allow this.  There are pet cemeteries where pets can be buried, for a price.)  Tyler was a too skinny grey 18-year-old cat.  He did not look a day over 3 or 4 months old.  My brother-in-law dropped him off at our house a few months ago because he's fixing his place up for sale.  My wife guessed that Tyler was here to die, and so he did. And he smelled.  B.O.  And he meowed, loudly.  None of the surviving pets liked Tyler.  I liked him.  My 2 year old son loved him as Tyler would not run away from him.  Now Tyler's gone.  We thought he was ready to die a few days ago so we took him to my wife's family vet.  I told the vet that Tyler seemed to be ready to die.  The vet disagreed and suggested that we do some tests on Tyler to the tune of $851.00!  He told me this with a smile on his face. (My brother-in-law was listening in on the speaker function on my cell phone.  He fell off his chair when he heard the dollar amount.)  What do you do in such a situation?  Do you spend whatever to try to prolong your pet's life?  Should the vet tell you that you will be spending a lot of money potentially in vain?   What is right and wrong here?   My brother-in-law asked for a less costly option.  This came to $250.00.  I've heard that veterinarian pricing is going up and up.