From what I remember from my Intro to Materials class, aerojels have to be made from a sol-gel process, meaning that at any period the quantity is going to be inherently small.  You have to introduce the right chemicals at specific periods so that the structure you want is made correctly.  It's a very delicate process. I'm not sure if there is a way to scale this process to the point it can be used for insulation purposes, but the material properties are phenomenal.