dude, separate your thoughts when you type. It's hard to understand exactly what you're asking us; sounds like a 6 year old trying to tell a story.
VERY BASICALLY put, you have three different types of speakers: Tweeters, midrange drivers, and subwoofers.
The point of having all of these is because at their cone and magnet size, the speakers are able to produce their intended frequencies optimally. High pitched sounds are very high frequencies. This is accomplished by tweeter's tiny sizes vibrating VERY quickly to produce the high frequencies. Subwoofers are NOT capable of this, as they are too big and heavy to move that quickly. This is the reason why you need the different speaker sizes for the different frequencies.
Like what notladstyle wrote: Subwoofers are meant to cover 25ish - 200 frequencies MAX. You do not really want to ever go under or above these for two reasons.
1. Most subwoofers are just incapable of it, and will overheat quickly if you do.
2. You probably won't be able to hear it at all or will sound like garbage.
These reasons basically go for the midrange and tweets as well, fall outside of their intended ranges and you'll get some nasty distortions or will be very low audibly.
Midrange covers everything that the Subs can't. Meaning, about 200-250 to up to around 1000hz.
Tweeters, obviously everything above that.
You get many benefits from multiple dedicated speakers:
Dedicated frequencies, optimal playback, increased volume without distortion, lower amount of stress on the components...
To answer your question above. Cheaper is never better. stay away from kicker if you want quality sound, unless you're willing to work hard to make them sound decent. If you just can't afford it, do what other people constantly recommend in this forum, just get a nice pair of component (non kicker) speakers up in the front stage of the car, just don't put anything in the rear.
Personally, I love having rear fill, the sound envelops me more and it feels "warmer" to me.
Also it lets the fuckers who sit in the back be able to hear well too.
You will need to see what you want to go for: SQ or SPL. From there, we'll be able to guide you along what components to choose from if you want to continue...