Reply to Starting up

So i'm sure there's been loads of these threads but I was wondering what you guys suggest I should get to help me with producing. As of now I have FL Studios 9 that I've had for over a year and lately have been trying to understand it more and more. My main problem is being able to put the idea I have for melodies into the program and producing the proper sound. I'm looking to spend about 400$ so could you guys help me out? thanks