Design a render - open to bidding

Hello, I am looking for a designer for interior renders. I will need 40 to 50 renders. I will ask a designer to design 1 or 2 and if i like the job he will ask him to execute all the renders. I like the renders you placed into your portfolio and i am wondering how much cost 1 render. How much you ask for 1 render, 10 renders and 45 renders. Best regards, Guillaume