What country are you in?
Most places ship internationally IME. (I'm in australia, I've only bought 1 or 2 vape related items here, almost all of it has come from overseas)
IMO, A silicone cover for the hydra-tube would do next-to-nothing.
For a small thing like the EQ bowl, It will absorb some of the shock and might prevent breakage, but for something as big/heavy as a hydra tube, I would think the silicone would need to be unpractically thick to offer any reasonable level of protection.
Honestly, I only ever saw the silicone covering as heat protection for my fingers...