my first box was £60, thick quality mdf with good terminals, carpeted, double 10"
however the carpet didnt stick on well and there was no central divider
i found a shop that sells electrical things and they sold me for £44 inc vat a TRIPLE 10" with 2 dividers, 20x3 cubic feet, i cut the carpet off each end and and it fits EXACTLY inbetween both wheel arches, id reccomend this to ANY fiat uno owner, it did take up 60% of the boot space, but was a nice enough shape to get the most out of my three 10" subs (which were incredibly loud and went down to 30hz)
even if youre poor you can afford this!
£22 for a single 12" and £18 for a single 10", or something like that, too
if you like the sound of this i can find you the exact prices, name of the place and website