your best bet is ebay, a wouldnt go to and audio shops for buying, fitting the prices are just ridiculos. vibe sbs with built in amps are canny they have a amp out aswell so you can buy another amp and power your other speekers for instance buy a 4 channel amp and get 2 sets of tweeter/components with cross over box this shud give u a decent system, its what i have aand im happy with it
u shud be lukin to pay about £400 also buy a decent head unit u shud be lukin to pay atleast £100 for a head unit i got mine of ebay shud of bin £280 new got it for £35 propa bargin
Hope this helped