In this place such things are done publicly and not in pm. If you want people to test run the casino with or without the $5, create a very nice or good announcement thread with good images will the link to the casino then you will have good number of people to test run the casino and not one sentence to invite people to a private pm to test the casino with $5.
You need people opinion about the casino then you have to drop the link to the casino which is the most important thing to do and when finally you have done everything in the casino, you can come back with a review campaign to get final feedback from the community or forum. You are welcome to the large number of gamblers forum.