Problem with insert statement

Hi there, i am having trouble inserting form fields into a database, it inserts the first 3 columns then just leaves all the rest blank and cant figure out for the life of me why, any help is appreciated, thanks.

the table columns are..
user_id | p_id | p_name | p_category | p_category_refined | p_condition | p_end | p_start_price | p_buyout | p_description | p_trade

Here is the form code

<form name="form" id="form" class="form" action="listitem.php" method="get" >
			<ul>
				<li>
					<label>*Product Name:</label>
					<input type="text" name="p_name"/>
				</li>
				<li>
		   			<label>*Product Category:</label>
		   			<select name="p_category" id="category" >
						<option value="">--</option>
						<option value="books">Books</option>
						<option value="equipment">Equipment</option>
					</select>
				</li>

				<li>
					<label>*Refine Category:</label>
					<select name="p_category_refined" id="categoryrefined">
						<option value="">--</option>
						<option value="php">php</option>
						<option value="java">java</option>
					</select>
				</li>

				<li>
		   			<label>*Condition:</label>
		   			<select name="p_condition">
		   				<option value="">--</option>
		   				<option value="new">New</option>
						<option value="used">Used</option>
					</select>
				</li>
				<li>
					<label>*End Date: </label>
					<input type="text" id="datepicker" name="p_end"/>
					
				</li>
				<li>
					<label>*Starting Price: (£)</label>
					<input type="text" name="p_start_price"/>
				</li>
				<li>
					<label>Buy It Now: (£)</label>
					<input type="text" name="p_buyout"/>
				</li>
				<li>
		   			<label>*Description: </label>
		   			<textarea cols="30" rows="4" name="p_description"/></textarea>
		   		</li>
		   		<li>
		   			<label>Sell option: </label>
		   			Sell<input type="radio" name="trade" value="sell"/>    
		   			Trade<input type="radio" name="trade" value="trade"/>    
		   			Both<input type="radio" name="trade" value="both" checked/>
				</li>
				<li>
					<input type="submit" value="Add New Item" />
				</li>
			</ul>
		</form>

And here is the sql statement that i am using. (the user_id and table name are defined in functions in other files)

$user_id = $user_data['user_id'];

$p_name = mysql_real_escape_string($_GET['p_name']);
$p_category = $_GET['$p_category'];
$p_category_refined = $_GET['$p_category_refined'];
$p_condition = $_GET['$p_condition'];
$p_end = $_GET['$p_end'];
$p_start_price = $_GET['$p_start_price'];
$p_buyout = $_GET['$p_buyout'];
$p_description = mysql_real_escape_string($_GET['$p_description']);
$p_trade = $_GET['$p_trade'];

mysql_query("INSERT INTO `ip_products` (`user_id`, `p_name`, `p_category`, `p_category_refined`, `p_condition`, `p_end`, `p_start_price`, `p_buyout`, `p_description`, `p_trade`)
				VALUES ('$user_id', '$p_name', '$p_category', '$p_category_refined', '$p_condition', '$p_end', '$p_start_price', '$p_buyout', '$p_description', '$p_trade')");


echo $p_buyout;
echo $p_category;
echo $p_category_refined;
echo $p_condition;
echo $p_description;
echo $p_end;
echo $p_name;
echo $p_start_price;
echo $p_trade;

The echo's wont be there once it works but when i tried to echo them out it only displayed p_name