Get a pioneer head unit, I used to sell them, they are really good quality and affordable. For speakers, if you are going to run them off the head unit, get four 6.5" 3-way pioneer 160 watt speakers.
If you want, you can go with pioneer 6.5" component speakers in the front, they sound really good and you can run them the same as any other speaker, right off your head unit. It is not hard to put in speakers or a head unit if you have patience. If you want the best sound, get a 4-channel amp and some really good speakers like MB quarts or something.