Магазин

using System;
using System.Collections.Generic;
using System.Linq;

namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            const int CommandShowDealerGoods = 1;
            const int CommandShowInventory = 2;
            const int CommandBuy = 3;
            const int CommandExit = 4;

            bool isRunning = true;
            Dealer dealer = new Dealer(0);
            Player player = new Player(90);

            Console.WriteLine($"{CommandShowDealerGoods} Посмотреть товары продавца");
            Console.WriteLine($"{CommandShowInventory} Посмотреть свои вещи");
            Console.WriteLine($"{CommandBuy} Совершить покупку");
            Console.WriteLine($"{CommandExit} Выйти из программы");

            while (isRunning)
            {
                Console.Write("Введите команду: ");
                int command = UserUtils.GetNumberFromUser();

                switch (command)
                {
                    case CommandShowDealerGoods:
                        dealer.ShowGoods();
                        break;

                    case CommandShowInventory:
                        player.ShowInventory();
                        break;

                    case CommandBuy:
                        player.BuyFrom(dealer);
                        break;

                    case CommandExit:
                        isRunning = false;
                        break;
                }
            }
        }
    }

    class UserUtils
    {
        public static int GetNumberFromUser()
        {
            string userInput;
            int userNumber;
            bool isNumber = false;

            do
            {
                userInput = Console.ReadLine();
                isNumber = int.TryParse(userInput, out userNumber);
            }
            while (isNumber == false);

            return userNumber;
        }
    }

    class Trader
    {
        protected List<Thing> Goods = new List<Thing>();
        protected int Money;

        public Trader(int money)
        {
            Money = money;
        }

        public void ShowGoods()
        {
            for (int i = 0; i < Goods.Count; i++)
                Console.WriteLine($"{i + 1} {Goods[i].Info}");
        }
    }

    class Dealer : Trader
    {
        public Dealer(int money) : base(money)
        {
            Goods.AddRange(new List<Thing>{ new Thing("Меч", 100), new Thing("Щит", 20), new Thing("Факел", 2) });
        }

        public bool TryGetPrice(int thingIndex, out int price)
        {
            price = 0;

            if ((thingIndex < 0) || (thingIndex >= Goods.Count))
                return false;

            price = Goods[thingIndex].Price;
            return true;
        }

        public Thing Sell(int thingNumber, int incomingMoney)
        {
            Money += incomingMoney;
            Thing selligThing = Goods.ElementAt(thingNumber);
            Goods.RemoveAt(thingNumber);
            return selligThing;
        }
    }

    class Player : Trader
    {
        public Player(int money) : base(money) { }

        public void ShowInventory()
        {
            base.ShowGoods();
            Console.WriteLine($"В кошельке: {Money}");
        }

        public void BuyFrom(Dealer dealer)
        {
            int price;
            Console.WriteLine("Введите номер вещи, которую хотите купить");
            int thingNumber = UserUtils.GetNumberFromUser() - 1;

            if (dealer.TryGetPrice(thingNumber, out price) == true)
            {
                if (Money < price)
                {
                    Console.WriteLine("Недостаточно денег");
                }
                else
                {
                    Money -= price;
                    Thing soldThing = dealer.Sell(thingNumber, price);
                    Goods.Add(soldThing);
                    Console.WriteLine($"В инвентарь добавлен {soldThing.Name}");
                }
            }
            else
            {
                Console.WriteLine("Такого товара нет");
            }
        }
    }

    class Thing
    {
        public Thing(string name, int price)
        {
            Name = name;
            Price = price;
        }

        public string Name { get; private set; }
        public int Price { get; private set; }

        public string Info
        {
            get
            {
                return $"{Name}\tЦена:{Price}";
            }
        }
    }
}