Here in Karachi there are a few shops specializing in insulation products. I might head that way in the not too distant future and would report what I see.
Insulation materials can be improvised upon by using carpet underlays, 'Namdas' as Reezvan said. Properties of each should be judged wisely.
Be very careful as anything which absorbs moisture has to be dealt with very very carefully. Always remember if by any chance you drive in heavy rains, you must make sure no water has made its way into the cabin, either via open windows or worse still if the pan has any holes. If in doubt pull out the whole carpet and let it dry up good.
A few years ago, I have had very bitter experience of losing half pans on both side because I had ignored damp carpets after my daily driver 68 was run for a very short distance in torrential monsoon rain. I just could not believe as the floors turned to Swiss cheese in a matter of days. Damp carpets and underlay combined with the fact that the floor was coated by Bitumen/coaltar, a hot favorite of our local denter bhais. Since that day, I swore no more coal tar for my cars. Ever.
Coal tar is a bad thing for the car. Good for our denter bhais. It hides all their follies, fills out small holes which should have been welded and gives any horrid metal with thick coats of rust a nice smooth black look. Car owner is happy, not knowing that beneath the layer, rust is creeping and eating away the metal.
There was a very nice thread somewhere on PWs which I saw recently saw in which a member experimented on the water absorbing property of some insulation material, commercial carpet underlay. The thread had a nice and informative Youtube link too showing his simple demo with a sample of the material.