sub and amp advice in a 172 cup!

[grwms]

id like a small sub and amp for use with my standard head unit, as i have the lead to work my ipod off it. does anyone know a decent one that:
A) isnt too big ( not looking for huge bass or anything, just summin to perk standard system up, and i dont wanna lose too much boot space)
B) isnt too expensive
cheers all.

 

[id_doug]

Something like this

http://www.justkenwood.co.uk/speakers01/kscsw1.asp

No idea what it would be like, but could fit your needs?!