Creating a damped proof/insulated area in garage

I have a large double garage of new build construction. The walls are a single brick thick with block pillars.

I'd like to use part of the garage as a storage area for some of my junk from the house. However the junk in question is reasonably valuable being my model car collection. This could seriously deteriorate if stored somewhere damp.

I do not want to do a habitable conversion. I just want to create a damp proof box in effect of about 4mx4m within the garage.

I'm looking for ideas about the easiest/cheapest way of going about this. I'm thinking about lining the floor/walls with dpm sheet, building a suspended floor, fitting a header plate to roof timbers and sole plate to floor, installing metal partitioning between the plates (I prefer working with this to timber), fitting insulation material then drylining.

But this does feel a bit over the top. Does anyone have any other ideas?

Thanks.

You'll probably get away with plastic boxes with lids. The really useful boxes that they sell in Staples etc are great for this kind of purpose.