[240 2NR]

A few additions to this post based on my experience

A hand pump is cheap, and jacking up you car is easy, though to do this properly you will need 4 jackstands (or still less money than taking it to the dealer).  Get the car up and level and remove the drain plug with a 1/2" square socket head (no socket, you may want some degreaser to clean the hole so as not to ruin the head, I used an extension so the torque wrench wouldn't get all nasty).  Drain to a catch container and clean off metal shavings from drain plug.  Reinstall plug and remove top plug to open filler hole.  Fill with fluid until the level is just below the bottom of the opening (that is the proper full level, check with your finger).  Over filling is not too dangereous as the first few times you drive, the vent at the top of the trans will just leak out the excess fluid and make the underside of you car all messy and the same with the floor (guess what my friend told me about the proper fill height just after I finished).  This means if you fill from above you must measure first and are assuming to have removed all the original fluid.

In the end with fluid and tools if you don't have them, it may be cheaper to go to the dealer.  But you will learn more and most likely use a better fluid (or bring some better fluid with you to the dealer) than if you have it done.  I used Amsoil series 2000 75-MT90 and have had no problems.  I love it.  Did the diff at the same time.  Others have commented that Mobil1 should be avoided on the trans.  Aside from the stock fluid, that's as much as I can comment on different kinds.