Unfortunately RobertQ is not so convenient to the casino...their drop-off location is on the Huron Church suburban strip.
Cheapest would be the Fort Street bus (1 1/2 hours (!), 1.50 US) to downtown Detroit, then the Tunnel Bus across, then walk to the casino. really only practical for the backpacker set.
Best would probably be RobertQ to their dropoff (Holiday Inn Select) in Windsor, then local cab to the casino.
Also possible would be cab or limocar from DTW right to casino (they post prices to Windsor...only problem can be finding a driver with a passport)