Good 4 Channel Amp
Good front speakers - 2 channels
Good sub - bridge the other 2 channels
8 gauge wring kit - http://www.ebay.co.uk/sch/GPS-InCar-Technology-/3270/i.html?_from=R40&_nkw=8+gauge+wiring+kit&_nkwusc=8+gauge+wring+kit&_rdc=1
I used to buy very average speakers, flipping from one brand to the next, then i invested in some Morel Tempo 6 speakers (retail around £180-190) real speakers, and have never looked. So in real terms although the initial outlay was more, its actually stopped my buying other gear.
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Morel
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captaincable is well known for selling Morel Tempo speakers on the cheap (realistically i should be telling you this) ... He ships on Fridays only if my memory serves me right.
http://www.ebay.co.uk/itm/Morel-Tempo-5-or-6-co-ax-speaker-set-BNIB-Far-superior-to-Focal-Access-/150967273538?pt=UK_In_Car_Technology&hash=item232659c842
Final word on Morel: I bought some Vibe components and in comparison to my Morel Tempo speakers, the Vibes sounded so c%*p that after a few days i ripped them back out and stuck the Morel Tempo 6 speakers back in ... that's how good Morel is!
DLS are forever winning EMMA SQ (Sound Quality) awards. Retail under £100 (the Morels retail for £180) DLS are by far and away the best sounding speakers I've ever owned!
http://www.ebay.co.uk/itm/DLS-Speakers-/190783825641?pt=UK_In_Car_Technology&hash=item2c6b9a26e9
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Subwoofer
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Forget about big figures when it comes to subwoofers at this level, for various reasons, in real terms it counts for nothing. I understand you want a sub with a built in amp to get you going. Personally I'd get on ebay and bid for a separate JL Audio subs and amp for a sub stage set up.
BTW, just to let you know, I build enclosures, and i replaced my 12" Digital Designs (competition subwoofer brand) with a 6.5" subwoofer from Hybrid Audio I6SW
http://www.buwaldahybrids.com/forum/showthread.php?22346-Just-Imagine-UK
And here's what PWK Designs (Peter W. Kulicki) did with the 6.5" subwoofer. i didn't believe it, os i bought one myself, and these little things hit hard!
http://www.youtube.com/watch?v=u8yArcObFZI - You;'ve gotta watch this!
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wiring kit
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The only issue I had with the pre-package wiring kit is that the RCA cable would always give way. So I invested in some 5m QED cable
http://www.ebay.co.uk/itm/QED-Performance-Audio-1-Phono-to-Phono-RCA-Cable-5m-/120792721264?pt=UK_Computing_Sound_Vision_Audio_Cables_Adapters&hash=item1c1fcea770
I know I might have over stretched your budget by a few pounds, but i've given what i feel is the best advice. best of luck my friend :).