Which gun is good to buy for a newbie?

I took a gun cl and shot with a 45. I ped the test I was taking but was not too satisfied. I want to become a better shooter. For my last round I shot someone 9 and it felt much smoother, not as much recoil so I was able to aim better. I want to purchase a 9 for this reason but have no idea which one. Any ideas? Can I get something for $400?