You might need to make your own 10-20 line module to do that. The one I made disables the add-to-cart button, so you can still kinda see it and can get familiar with where it's going to be. Then when you're ready to sell just disable the module. The module determines if the node is a product and has a add-to-cart form on it. If it does, utilize the disabled key in the add-to-cart form {
$form['submit']['#attributes']['disabled']="disabled";
// unset() or change other stuff here
}