Get lease offers yourself? If so, where?

Hello, I am about to lease a vehicle on business. BJ 08/2015 50 tkm on the speedometer 36 months leasing 25 tkm p.a. All prices in gross: Current selling price = 40,000 euros. Estimated residual value after 36 months = 20,000 euros (I already hold for too low). Comparable models with 125,000 km are just for 30,000 to 35,000 euros at mobile.de. Monthly rate would be 670 euros x 36 months = 24,100 euros. So pay 4100 euros for the “financial service” since the car is only 2 0.000 in value loses. So almost 20% calculated on 3 years, which I think is too much. Does someone know banks or portals where I get a better offer? Thanks already and many greetings!