new Menu:ammomenu; //before main()
//----OnPlayerCommandText
if (!strcmp("/buy",cmdtext,true,10))
	{
	new Float:x;
	new Float:y;
	new Float:z;
	GetPlayerPos(playerid,x,y,z);
	if (279<x<316){
	if (998<z<1005){
 	    if(IsValidMenu(ammomenu)) ShowMenuForPlayer(ammomenu, playerid);
		 }
		 }
		else {
				SendClientMessage(playerid, COLOR_YELLOW, "You are not in ammunation.");
			}
 	    return 1;
	}
//with other publics
public OnPlayerSelectedMenuRow(playerid,row) {
    new Menu:Current = GetPlayerMenu(playerid);
    if(Current == ammomenu) {
        switch(row) {
            case 0: WeaponBuyGren(playerid);
            case 1: WeaponBuyTear(playerid);
            case 2: WeaponBuyFlame(playerid);
            case 3: WeaponBuyMini(playerid);
            case 4: WeaponBuyRckt(playerid);
            case 5: WeaponBuyHeat(playerid);
        }
    }
    return 1;
}
//before player classes
ammomenu = CreateMenu("Ammomenu", 2,  200.0, 100.0, 100.0, 50.0);
SetMenuColumnHeader(ammomenu, 0, "Type");
SetMenuColumnHeader(ammomenu, 1, "Price:");
AddMenuItem(ammomenu, 0, "Grenades");
AddMenuItem(ammomenu, 0, "Teargas");
AddMenuItem(ammomenu, 0, "Firethrower");
AddMenuItem(ammomenu, 0, "Minigun");
AddMenuItem(ammomenu, 0, "RocketLnchr");
AddMenuItem(ammomenu, 0, "HS RocketL");
AddMenuItem(ammomenu, 1, "300$");
AddMenuItem(ammomenu, 1, "500$");
AddMenuItem(ammomenu, 1, "10000$");
AddMenuItem(ammomenu, 1, "20000$");
AddMenuItem(ammomenu, 1, "10000");
AddMenuItem(ammomenu, 1, "15000");
//that's all, works for me