Edit in JSFiddle

angular.module('shopping',[])
			.directive('validPrice',function(){
				return{
					require: "ngModel",
					link: function(scope, elm, attrs, ctrl){
						
						var regex=/^\d{2,4}(\.\d{1,2})?$/;
						ctrl.$parsers.unshift(function(viewValue){
							var floatValue = parseFloat(viewValue);
							if( floatValue >= 50 && floatValue <=5000 && regex.test(viewValue)){
								ctrl.$setValidity('validPrice',true);
								//return viewValue;
							}
                            else{
							    ctrl.$setValidity('validPrice',false);
                            }
							return viewValue;
						});
					}
				};
			});
  
	function ShoppingCartCtrl($scope, $window)  {

		$scope.item = {};
        
        var errorMessages={
							name:function(){
										required="Name cannot be left blank";
										pattern="Name cannot contain numbers or special characters";
										
										return{
											required: required,
											pattern: pattern
										};
									}(),
							price:function(){
										required= "Price cannot be blank";
										validPrice="Price should be a number between 50 and 5000 with maximum 2 digits after decimal point";
										
										return{
											required: required,
											validPrice:validPrice
										}
									}(),
							quantity:function(){
											required="Quantity cannot be blank";
											validQuantity="Quantity should be an integer between 1 and 90";
											
											return{
												required: required,
												min: validQuantity,
												max: validQuantity,
												pattern: validQuantity
											}
										}()						
						  };

		$scope.failedValidations = [];

		$scope.addItem = function(item) {
			$scope.failedValidations = [];
            errorMessage="";
            
            if($scope.itemForm.$dirty && $scope.itemForm.$invalid){
                for(validations in $scope.itemForm.$error){
					for(count=0;count<$scope.itemForm.$error[validations].length;count++){
						$scope.failedValidations.push(errorMessages[$scope.itemForm.$error[validations][count].$name][validations]);
					}
				}
			}
            else{            
				$scope.itemForm.$setPristine();
                //Submit the values to server
				$scope.item = {};
			}
		};
        
		$scope.name=/^[a-zA-Z ]*$/;
		
        $scope.integerval=/^\d*$/;
	}

<div ng-app="shopping">
		<div ng-controller="ShoppingCartCtrl">
			<form novalidate name="itemForm">
				<table>
					<tr>
						<td>Name: </td>
						<td><input name="name" type="text" ng-model="item.Name" required ng-pattern="name" /></td>
					</tr>
					<tr>
						<td>Price: </td>
						<td><input name="price" type="text" ng-model="item.Price" required  valid-price /></td>
					</tr>
					<tr>
						<td>Quantity: </td>
                        <td><input name="quantity" type="number" ng-model="item.Quantity" min="1" max="90" ng-pattern="integerval" required /></td>
					</tr>
					<tr>
						<td colspan="2"><input type="Button" value="Add" ng-click="addItem(item)" /> </td>
					</tr>
				</table>
			</form>
<div id="errMessages" class="errors">
				<ul>
					<li ng-repeat="message in failedValidations">{{message}}</li>
				</ul>
			</div>
		</div>
	</div>

.bold { font-weight:bold; }

table td{
    padding: 10px;
}

table th{
    font-weight: bold;
    text-align: center;
}

span[ng-show]{
    color: #FA787E;
}

.errors{
	color: #FA787E;
}