Aerogel is great stuff...the only problem is $$.
for a 1" thick comparison:
Polyisocyanurate: R-value is 6.5 and cost is $0.63/square foot
Aerogel: R-value is 10.3 and cost is $46/square foot.
So if you want to have an R30 insulated Box, you would need 3" of Aerogel or 4.6" (round it up to 5") of Polyiso. I haven't done the math on what it would cost to insulate an 8 Cubic foot box with 3" of Aerogel and compare that to polyiso, but if you have the space for 5" of polyiso you could save a LOT of coconuts.
The one square foot price
difference between 3" of Aerogel to 5" of Polyiso is like $172.5 to $3.13. Now it's early and my math brain maybe hasn't woken up yet, but I'm using the Ebay price
of Aerogel at $23 per square foot for a 10mm (0.4") piece compared to the Home Depot price
of polyiso at $20 for 32 square foot sheet (4ft x 8ft 1inch thick). Am I smoking crack...or are those cost numbers about right....yawza...
Another way to look at it on a $/R-value:
(used $172.5 for R30.6 for Aerogel and $3.13 for R32 for Polyiso)
That is a 56 Times higher cost...Aye Crumba...
Now of course there are other benefits to Aerogel other than R-value, but you can never really take COST out of the equation or you end up debating how many angles will dance on the head
of a pin because normal people couldn't afford it anyway.
What have others found working with Aerogel in terms of cost per R-value.
Unless someone just doesn't have the space, my preferred recommendation for someone redoing their Box insulation
would still be Polyiso based on the cost differential.