I think everyone is telling you to make a plan because it appears that you are purchasing snakes and then asking questions about them rather than the other way around. You have a female ghost and plan on getting a male. That will work well, but you also have two females. If you got a pastel male you could breed him to the two females and that would also work well. If on the other hand you got the het albino pair, the two females would just be sitting around taking up space for the most part. I wouldn't buy anything else until you know exactly what you want out of these animals.

PS- The whole "i'm in med-school so I know what I'm doing" thing just makes you look like a tool.