Average price of 7-14 seater with driver in Osaka?

Any idea what the average cost of a 7-14 seater in Osaka including driver for 12 hours per day? We will be there April 11-21. Whenever I post something in FB, I get bombarded with PM's and the price range varies wildly. Then I read some posts that some bait you with really cheap options then gets you back once there. I know Japan is known for honesty, so was wondering what the acceptable price is without offending locals and legit operators.