Long long time ago, I installed Customshippingrate module, but never made it work on my site. The module sits on the disk but disabled. Recently I took some trouble and about three days developing my own module Cush for admin panel users to charge special shipping price when creating an order.
Cush module does not override any Magento classes so it is virtually 100% compatible with other modules. Neither does Cush module override any Magento templates so basically it reuses Magento native interface. Cush is not a shipping method so it can work with any Magento shipping methods or 3rd party shipping methods.
Cush module injects customisation logic by javascript. What it actually customise are values in magento_sales_flat_quote_shipping_rate where is pool of shipping quotes. Values customised belong to an individual quote so the customisation hits its point.
When writing Cush module, I found a defect in Magento own code app/design/adminhtml/default/default/template/sales/order/create/shipping/method/form.phtml.
echo $this->getCarrierName($_rate->getCarrier());
The above code reads value from configuration and shows it as carrier title. If I was not injecting shipping method customisation logic, I would not realise it is a defect. Carrier title value, like method title and shipping rate, if read from magento_sales_flat_quote_shipping_rate using $_rate->getCarrierTitle(), will make more sense. Values from configuration will not reflect carrier title changes done by Cush. I respect Magento own templates, especially adminhtml templates. Instead of overriding this template, I wrote some additional javascript in Cush module to correct carrier title. I stick to my green principle although it costs much more time developing.
Upon installing Cush module, I removed all files of Customshippingrate module. A small accident happened – can not create shipment. It turns out during creating shipment, Magento is gathering all config paths start with “carriers/” and working out all carriers between two slashes. It is a bad logic, or I can call it a bug. It does not check whether this carrier exists or is active. So, very bad.
Just add to my Magento caveats: after removing a shipping method, remove all entries of “carriers/CARRIER_CODE/*” in magento_core_config_data.