Semen Tanks

I'm looking into getting my own semen tank. Just curious as to your opinions on which tank is the best for my situation. I need a small to medium tank. I only have about 4 cows that I for sure want to AI every year, but I feel that I would have a few more if I had my own tank. What are your experiences with tanks. How long does the liquid nitrogen last and how much per fillup? How do you like your tank?

Thanks

in my experience, you can never have a 'big enough' semen tank...  i started out the same way-- one tank- few straws... then after a couple of years.. I've worked up to three tanks, and still not enough room I don't think. 

Unless you have a good source of N-- they are costly to upkeep.  Going to be around 200 to fill it a year. 

I have two MVE 20/20 tanks- and one Millennium. I think they are about equal in terms of advantages.

Get a tank with the longest holding time possible.  I agree, you can never go too big.