Cheapest would be to hijack some space on a container, but still going to have GST and state duties on top (maybe $1000) plus the container space.

I shipped two BBB's together by air, didn't gain anything from the shipping (the only area you'd possibly save with multiple games). Cost about $2K each IIRC. Suspect about $1500 if boat. Just guessing, some here will have more recent experience I suspect.