What parts are really required to motorize 10219 Maersk Train? The Official site detailed page states that:


  Motorize your Maersk train by adding LEGO Power Functions #8878 Rechargeable Battery Box, #8887 Transformer 10V DC, #8884 IR Receiver, #8879 IR Speed Remote Control and #88002 Train Motor!


So:

8878
8887
8884
8879
88002


Is it true that I need all of them (costs ~$150) to motorize the train, or can I omit some?
The strict minimum you need for PF motorization is:


Tracks. Sounds obvious, but don't forget these. Nope, there are none with the Maersk train.
A PF train motor
A PF battery box (plus 6 AAA batteries)


Now, as oezi says, it's a bit senseless to have a train which you can't control. Well, you can control it, but it's limited to switching it on and off (if you can catch it). Yet, it's a start.

Now, as far as limited control goes, don't neglect the polarity switch! If you place it intelligently, it will be easier to stop your train. Or you could even mimic the old 4,5v system and have your train switch direction automatically at both ends of a track. Just a thought.

Of course, for more serious control, yes, you'll need:


PF IR receiver
PF IR speed remote control


Note that all these elements (tracks, motor, battery box, IR receiver and remote) are also present in these trains:


Passenger Train
Cargo Train
Red Cargo Train (red battery box)


So it may be worth to do the math and see if you're not better off just buying one of these. Sets are usually cheaper than standalone elements, and considering the extra parts you'll get, it may be a wiser investment. Not to mention that they may be easier to find in regular shops, which means maybe Christmas discounts and the like. And the design of these trains is quite good too.

Of course, batteries are going to be a problem, so if you don't want to sink too much money in them you'd better use rechargeable batteries as fast as possible, or yes, switch to:


PF Rechargeable Battery
10VDC transofmer - or use a cheaper one


As you can see, it can be a costly investment in the long run, but nothing forces you to buy it all in one step, especially the rechargeable battery and charger which are far from cheap.