Looking at the pics of those tents I reckon that you could probably make yourself a bunch of them with Papier Mache. Use some expanded polystyrene to make a very basic shape and cover that in plasticene or something similar to get the right shape. Don't know if the Papier Mache would stick to the plasticene or not, but to be safe, maybe cover it with a sheet of clingfilm. Tissue paper, and either watered-down pva or a flour/water mix (I'd probably go for the former), apply a few layers, let it dry thoroughly and lift from the Former and you would have a tent shape. Base it, add a couple of cocktail stick tent poles, and you are done.
If you don't think that would be robust enough, some thin card from cereal boxes could be embedded in the Papier Mache. Even stronger, use wire mesh used for small animal cages to create the structure to support it.
Al