Now, i'm not sure what he meant by "component speakers" for front. I get a feeling he's only trying to sell you something.
First off, you need to decide what kind of sound you want...for example do you like to play it loud, whether you want deep, thundering, car-shattering bass and so on. If not then the HU and usual speakers have enough juice to give you decent sound.
IMO get good quality coaxial (NOT "dual cone"), and 3-way if possible, speakers for the front - get the biggest ones that will fit (or alternatively see if you can have them fitted in the doors or a larger enclosure). For the rear the usual 6x9 coaxials (3-way would be best). This will cost almost nothing, since you already have the HU and rear speakers, the only additional cost would be for the front coaxials. You can use components with HU directly, IMO. If you use all 4 channels of the HU without the HPF/LPF function then you will need comps for all four (basically one component speaker and a tweeter per channel), along with crossovers (depending on tweeter a crossover may/may not be needed).
If you plan to use the LPF/HPF function then front stays with the coaxials and for rear get woofers (4 ohms rated). See if you can fit the 6x9 meant for the rears into the front somehow for this option - that way you won't have to buy new speakers for the front.
The above will be the most cost effective and easily fit within your 6-7k budget, and at the same time sound very nice indeed. To summarise, I am suggesting getting only the required speakers (or woofers or components), and no amplifier(s).
However, if you want car-shaking sound (or people looking at you!) you need a dedicated sub (with an amp for it) and components. Components go in the front and/or rear and subwoofer sits somewhere in the boot. Of course these will need amps - if you have components you will need a crossover too, in addition. If you want comps in front and rear, a 4-channel amp will be needed for this, else a 2-channel amp. Subwoofer will need its own amp (or get a powered sub which has the amp built into its box). Look at other threads for brands - unfortunately I cannot suggest them. Once you have decided upon this, next comes all the wiring and stuff - this needs to be done professionally so that it does not hamper the car's other major electrical systems. Also you will most probably need to stretch your budget if you go this way. The amps themselves might cost upwards of 3k each (and I'm being very conservative here) - so one amp each for the comps and subwoofer will itself drive the budget to about 6k or more. Then there is the cost of the component speakers and the subwoofer, and the crossover and the wiring kit, and so on...basically you're looking at a 10k+ budget.
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