I got my grav guns from anvil industries. I used their ion rifle as my grav guns.
You can drop a single attack bike to get the shield.
You are aware that razorbacks are fragile. As you said, they have been working for you -- so if its not broke don't fix it.
If your using typhoons for fire support, look at centurions. Instead of 75 points for 2 missiles, your paying 90 points for 1
ML and 1
TL LC. I would argue that a centurion is much more durable than a AV10 skimmer.
I wish termies were good in this codex, but they are overpriced.
Something you might want to consider is allying with yourself. Basically use your main list as "Iron Hands" or "Ultramarines" or something and then use "White Scars" for your bikes. A lot of your units are not getting as good of a boost from them white scars
CT, and there is no need to limit yourself to them.
If your looking for a cheap
IC you can take a
MotF. On the other hand, Tigerious is really money for his points.