I have no idea what exists on the lower end of the scale, including older technologies. Where I'm at, a modern chip putting out 50hz with auto non-uniformity correction is going run you ~$7000 while goggles are about double or more (collimation and bridging gets expensive). I am in Canada, but you don't save much in America either.
I actually got a chance to demo PVS-31's with clip-on thermals - great stuff, but very front heavy and bulky. Whiplash injuries with advent of helment-mounted NVG's has always been a problem and it's going to get worse unless more effort is put into reducing size/weight. Iirc Act in Black of Luxembourg makes some of the lightest, durable dual-tube NVG's today. The very high-end shit from L3 uses a small, integrated germanium lens which solves this, but access is limited to super sekrit government work.
As for the space blanket, you actually don't need much space at all - just enough insulative layers, the Mylar and some kind of adhesive (Velcro) to prevent the layers from separating.