The Aerotech rc casing is machined from solid bar stock, not tubing since it has a solid end, so is more time and expense to make, I normally sell the casings at around $60 when I can get them, I personally would never risk an Estes 24mm E bp motor in any of my RC rcrgs that have $150-$200 invested since I've seen too many personally fail in a way that destroys models, I've had 0 failures in over 1000 e6 flights in 3 casings just in the last 3 years, to me it's foolish economy, but to each his/her own.
It's too bad that being in Hawaii you can't have the reloads shipped USPS ground which makes the reloads not much more than Estes motors.