why does everyone always head higher up the price range to the posh new kit?
OK, heres the Real budget basement version for literally just a few quid!
I'm going to suggest what I would do on a very tight budget, infact I did do this as a scout 30 years ago with around £5!
buy 2 to 4 of the cheapest rollmats you can find, they will be too short and they will be thin.
(places like poundland/99p shop have sold them before).
Get hold of some bubble wrap or in an ideal situation the foil coated bubblewrap used as house insulation.
(you might be able to find this for free or it can be bought from DiY shops and often in Poundland/99p shops )
Buy a roll of Duck tape/duct tape/tank tape, that thick fabrc tape you can fix anything with don't worry too much about the brand, they nearly all have faults!
(again poundland and 99p shops sell it)
1) Place 2 of the roll mats on the floor to create a sleeping area long enough for you to sleep on, tape them so they stay together in this position.
2) next measure out the bubble wrap ontop of the rollmat layer. Tape the bubble wrap pieces it together to make a sort of bubblewrap mat the same shape as the roll mat
3) Tape the bubblewrap to one end of the created roll mat, (end "A") but not along the long edges.
4) copy stage 1, make a top rollmat layer, when done tape firmly on end "A" the same as the bubble wrap.
(whilst you're at it, you could add a layer of Mylar those silver survival blankets marathon runners are given, again sold in pound shops!)
5) add bands of tape going right around the 3 parts going across the finished mat this should hold it all in place.
6) roll up the mat as one, you may find you can tape along the sides if it's flexible enough, but you'l probably find it will come loose, when it's rolled up.
The top and bottom rollmats provide insulation both protect the bubblewrap from thorns and accidental and "boredom" popping.
The bubblewrap provides a soft layer much like those self inflating ones....
OK it's not going to be pretty, and the main downside is it will be bulky, but it will definately be warm and far more comfortable than many of the stiffer army mats you could buy.
If you wanted to secure it all you could make a cover for the whole "rollmat sandwich" from a folded and tucked in old bed sheet.
you could even glue or tape a thick PVC layer on the base, attatch your sleeping bag perhaps with paracord laces to the mat all of a sudden you start to head towards a Australian type Swag bag design!
and all for only a few quid!
I've used an airbed and a thermarest both with a puctures, they were not warm or comfortable nights! Yes, thermarest does provide good insulation and some when it leaks but hardly any when you're squashing a flat one!
A roll mat will always win hands down for warmth sadly they are just not as comfy!
) decided to spend the money on a bit insulated sleeping pad (Vaude Norrsken). Never slept better when out camping, and that in itself made it worth the investment. It also packs up pretty small, but 30L is always a bit small unless you start going for expensive ultralight equipment. 
