How do I make an interactive jukebox that plays songs based on collectables?

I am making an interactive jukebox and trying to set it up so that it plays based on what collectible record items the player has found in the level. Right now I just have it set up to play a song by pressing E when in range, and it does this by activating the game object specified that has the audio source component. This is probably not the cleanest way to do it. So, how do I do the following:

1: Make it cycle through available songs based on records collected 2: Make it skip songs if the player didn't pick up that record collectible 3: Display a message if the player has no record collectibles.

Below is what I have so far, any direction would help.

using UnityEngine; using System.Collections;

 public class GramJukebox : MonoBehaviour
 {
     //setup guitext, song gameobjects, and the range flag
     public GUIText TextOutput;
     public GameObject Song0;
     public GameObject Song1;
     public GameObject Song2;
     public GameObject Song3;
     private bool InsideCollider;
 
     //Player enters trigger volume
     void OnTriggerEnter (Collider other)
     {
         //Turn on flag for being in range of gramaphone
         if (other.tag == "Player") {
         InsideCollider    = true;
         }
     }
 
     //player exits trigger volume
     void OnTriggerExit (Collider other)
     {
         //turn off flag when player leaves range
         if (other.tag == "Player") {
         InsideCollider    = false;
         }
     }
 
     void Update () {
 
         //When the player presses E while in range
         //Play song
         //Show name
         //Go to next song if pressed again
         if (Input.GetKeyDown (KeyCode.E) && InsideCollider == true) {
         //turn on gameobject with song
         Song0.SetActive (true);
         //Update the GuiText
         TextOutput.text = "Now playing... Song0";
         }
     }
 
 //final brace because sometimes I'm a derp
 }