go with bose or alpine :P

alpine head unit
mid-range amp
10" sub in a box

i dont know how much 200quid is in USD but i presume you don't want to dump a bunch of money into your sound system, headunit is a must if you want to cut back on an amp and sub.

___________________
I PUT TRADEMARKS AROUND YO MOTHAFUCKIN EYE
JUST ME N YOU

You wont get anything decent for that, but we all had to start somewhere.

Cheapest bet is to get a 10" or 12" bass tube.
These come with a built in amp and are easy to set up.

Don't cry if it sounds like crap or after two weeks the speaker in it blows, you get what you pay for.

A 10" sub is more punchier bass, a 12" sub, whilst still providing a good punch, is for lower frequencies, deeper bass.

I think this place is local to you http://www.audiopipe.co.uk/ you will probably find cheaper places though.

Try not to get credit (higher purchase) I did it and it took me about 7 years to fully pay it off. I ended up witha good system right enough.