using System;

using System.Linq;

using System.Collections.Generic;

using Newtonsoft.Json;

using Newtonsoft.Json.Linq;

public class Program

{

    public static void Main()

    {

        var json = "{ \"price\": [ 10, 20 ] }";

        var json2 = "{ \"price\": 15 }";

        var foo1 = JsonConvert.DeserializeObject<Foo>(json);

        var foo2 = JsonConvert.DeserializeObject<Foo>(json2);

        foo1.Price.ForEach(Console.WriteLine);

        foo2.Price.ForEach(Console.WriteLine);

    }

}

​

public class Foo {

    [JsonProperty(PropertyName = "price")]

    public dynamic priceJson { get; set; }

    private List<int> _price;

    public List<int> Price {

        get {

            if (_price == null) _price = new List<int>();

            _price.Clear();

            if (priceJson is Newtonsoft.Json.Linq.JArray) {

                foreach(var price in priceJson) {

                    _price.Add((int)price);

                }

            } else {

                _price.Add((int)priceJson);

            }

            return _price;

        }

    }

}

​

​