Patch for combatability with UC Custom Price

Attached is a patch that lets this module work w/ uc_custom_price.

A cool use case is to have the product set as "call for pricing". When they contact you, you can send them an ubercart "cart link" that looks like:

yoursite.com/cart/add/e-p98_q5?destination=cart&price=100

The number (98) after the "p" is the node id, the number after the "q" (5) is the quantity, the "e" empties the cart, and the 100 after "price" is the price you want to set.

Then use uc_custom_price with this code:

$price = $_GET["price"];
if (isset($price)){
  $_SESSION['mycustomprice'] = $price;
  $item->price = $price;
}
else if (isset($_SESSION['mycustomprice'])) {
  $item->price = $_SESSION['mycustomprice'];
}
else {
  $item->price = $item->price;
}

You have a product w/ "call for pricing" that you can send a link to people so that they can buy it.