I also have a small club calf operation that is just getting started and I just got a MVE tank. I will attach the link to the tank I got. It is the Millenium 2000 XC 20. I think it has a 120 day duration on liquid nitrogen. It is also one of the cheaper models. I got mine through Cattle Visions filled and with my semen in it. Picked it up at the Ohio Beef Expo.