Dust Notes.
Cost - Quite expensive. In the hundreds.
Keep them calm. Reassure they're okay. Use a gentle tone; touch and feel them.
Suggestion. Suggest things are their idea. Agree. Try not to excite them too much. Keep them calm, as I stated.
 Time - It lasts about 1 - 2 hours, give or take. More than enough time for me.
This should be enough to not wake them up, and get your money's worth.