Out of touch... please help me design a simple system

[BailOut]

I have never cared much for the stock stereo system and as luck would have it mine just stopped playing CDs. The timing is perfect as I just passed the warranty period for it. heh

I haven't looked into car audio in more than a decade so I am completely out of touch with the scene. I don't need anything elaborate... no subwoofer, no amp, no GPS, etc. but I would love a double din that can play MP3, videos, etc. and a new set of speakers to accompany it. I also want to keep the power requirements low (~ 250W) so as not to impact fuel economy by placing a large load on the electrical system. I have been reading through this forum for a while, trying to get a sense of things, but it is difficult as the technology moves so fast and so much of this stuff is more opinion than fact. As such I would appreciate some direct advice.

Price is a factor as this venture will require my wife's approval but I can do the installation myself and can spend about $500. I am not set on buying anything from eBay but that's where I found good links at, so that's what I'll post here. I am totally open to suggestions:

Head unit: EONON 1091 7"LCD MONITOR IN DASH DVD TV PLAYER I like this one not only for the price but because it plays AVI files which is not a seemingly common thing. I have a ton of movies and music videos in this format. I know that Eonon is not a high end manufacturer but I'm not a high end kind of guy.

Speakers: JL AUDIO TR650-CXI 6 1/2" COAXIAL SPEAKERS 6.5 TR650CXI or KENWOOD 6.5" 3-WAY CAR STEREO SPEAKER SYSTEM. Their power ratings match the head unit nicely, and I am thinking of going with 6.5" in both the front and rear. I like that the Kenwoods are 3-way, too.

I know I will also need a double din dash kit (I'll get it from the sticky), a wiring harness (I'll get it from the sticky) and spacers for the speakers, but I have no idea if additional mounting equipment will be needed (especially with going from the stock 5.5" speakers in the rear to 6.5").