public class RegionRaion
    {
        public int Id { get; set; }
        public  decimal Price { get; set; }
    }

    public class PriceController : Controller
    {
        [HttpGet]
        public ActionResult PriceGet()
        {
            RegionRaion regRai = new Models.RegionRaion();
            regRai.Id = 1;
            regRai.Price= 123.45M;

            return View(regRai);
        }

        [HttpPost]
        public ActionResult PriceGet(RegionRaion regRai)
        {

            return View(regRai);
        }

    }

@using (Html.BeginForm("PriceGet", "Price", FormMethod.Post))
{
    @Html.AntiForgeryToken()
    
    <div class="form-horizontal">
        <h4>RegionRaion</h4>
        <hr />
        @Html.ValidationSummary(true, "", new { @class = "text-danger" })
        @Html.HiddenFor(model => model.Id)

        <div class="form-group">
            @Html.LabelFor(model => model.Price, htmlAttributes: new { @class = "control-label col-md-2" })
            <div class="col-md-10">
                @Html.EditorFor(model => model.Price, new { htmlAttributes = new { @class = "form-control" } })
                @Html.ValidationMessageFor(model => model.Price, "", new { @class = "text-danger" })
            </div>
        </div>

        <div class="form-group">
            <div class="col-md-offset-2 col-md-10">
                <input type="submit" value="Save" class="btn btn-default" />
            </div>
        </div>
    </div>
}

.................................................................................................
            <div class="form-group">
                <label asp-for="Price" class="control-label"></label>
                <input asp-for="Price" class="form-control" />
                <span asp-validation-for="Price" class="text-danger"></span>
            </div>
.................................................................................................

            <div class="form-group">
                <label class="control-label" for="Price">Price</label>
                <input class="form-control" type="text" data-val="true" data-val-number="The field Price must be a number." />
                <span class="text-danger field-validation-valid" data-valmsg-for="Price" data-valmsg-replace="true"></span>
            </div>

<input asp-for="Price" class="form-control" data-val="false" />

.......................................................................................
        [RegularExpression(@"^\d{1,18}(\,\d\d)*$", ErrorMessage = "Ошибка ввода!")]
        public decimal Price { get; set; }
.......................................................................................