Hi Jeff,
All of the above suggestions are good suggestions, and I would like to add a suggestion of mine here.
I have carried several bottles of ink successfully just in a carry-all. Put a boxed bottle of ink in a compartment, and stuff some buffeting material around it, like a plastig bag, or bubble plastic. That's all I have been doing for the last 3 years or so, and I carry at least 5 and up to about 10 bottles of ink with me that way, all together in a compartment, and accompanied by other stuff. Unless you start throwing your bag around in a really bad way, or dropping it from elevated levels, it shouldn't pose a problem. All ink bottles have sealing caps, and glass is sturdier than many people think, and even more so when there is some shock-absorbing material around it.
Don't forget: ink gets transported all over the world in bigger boxes containing the smaller ink bottle boxes, with a little bit of shock-absorbing material only.
So, that should work too

.
if you're worried about a leak, just stuff the bottle and box in a jiffy bag first, maybe with some paper toweling in the jiffy bag to buffer the worst leaks.
HTH, warm regards, Wim