I talked with Chris Bowen about a Hawaii NBTHK shinsa back in 2012, & here's what he said:
Thanks for your interest.
In the past, the NTHK has wanted a guarantee of at least 300 items before they will commit to coming. We set the cost of the shinsa to pay for their usual shinsa fee, plus all the expenses involved in bringing them, which includes air fare, hotel, etc. I received a percentage as well for my time and expenses in setting up the event (venue, advertising, security, etc.), my translating and assisting them while in country (picking them up at the airport, taking them shopping,etc.).
I have been approached before by people in Australia and the UK. The stumbling block has always been the guarantee. We have had no trouble getting 300 items at our stateside shinsa in the past, then again, they have always been 6-7 years apart...
Let me know if I can be of any more help.
and one follow-up:
The fee would be about $300 per item. This would cover their fee and cover my time and expenses. We charged $350 I think for items that passed at the last shinsa, and the extra $50 per item paid for their airfare, hotel, etc.
I would be very surprised if you could manage to get the NBTHK to come to the US for a shinsa. People have been proposing that to no avail for a loooong time.....
A bit of market research to sound out interest would be a great idea....Let me know how things go and if you have any further questions.
Not sure how much has changed since 2012, but at least here are some hard numbers.