prontera,150,150,5  script  ExchangeAgent   99,{
 
set .@itemid,674; //Exchange/Receive item (Mithril Coin = 674)
set .@name$,"[Exchange Agent]"; //npc dialogue name
set .@cost,100000000; //cost per mithril coin & zeny received when redeeming
 
mes .@name$;
mes "Hi, and welcome to my Exchange Shop.";
mes "What can I do you for?";
switch(select("Zeny into Mithril Coins:Mithril Coins into Zeny:Exit")){
    case 1:
        mes .@name$;
        mes "Hello, I can give you 1 Mithril Coin for 100'000'000 Zeny.";
        mes "Would you like to continue?";
    if(select("Yes:No")==2) close;
    if(Zeny < 100000000) close; //If less than 100m close
    next;
        mes .@name$;
        mes "Please input how many coins you'd like to purchase.";
        mes "Input 0 to cancel.";
    input .@input;
    set .@calc,.@cost*.@input;
    if(.@input == 0) close;
    if(.@calc > Zeny) close;
    next;
        mes .@name$;
        mes "You wish to exchange "+.@calc+" Zeny to "+.@input+" Mithril Coins?";
    if(select("Yes:No")==2) close;
    next;
        mes .@name$;
        mes "Processing Transfer..";
    sleep2 500;
    set Zeny,Zeny-.@calc;
    getitem .@itemid,.@input;
    sleep2 500;
        mes "Process Completed.";
    close;
    case 2:
        if(countitem(674) < 1) close; //check if no mithril coin it closes, why bother with other crap..
        mes .@name$;
        mes "How many would you like to turn into Zeny again?";
        mes "Press 0 to cancel.";
    input .@input;
    if(.@input == 0) close;
    set .@calc,Zeny + (.@input * .@cost); //Calculates if more than 2b
    if(.@input > countitem(.@itemid)) close;
    if(.@calc > 2000000000) close;
    next;
        mes .@name$;
        mes "You wish to turn "+.@input+" Mithril Coins into Zeny?";
    if(select("Yes:No")==2) close;
    next;
        mes .@name$;
        mes "Please wait.";
        mes "Processing..";
    next;
        mes .@name$;
        mes "Please wait.";
        mes "Processing...";
    sleep2 1000;
    delitem .@itemid,.@input; //Deletes item
    set .@zeny,.@input*.@cost; //calculates amount to be received
    set Zeny,Zeny + .@zeny;
    sleep2 500;
        mes "...";
    sleep2 500;
        mes "Transaction Completed.";
    close;
    case 3:
    close; //not going to bother with text here..
}
}