*How to Implement your own Custom Shipping options?*

We sometimes use UPS & FedEx, but we also fill sea freight containers filled with products. Prices are not always the same for each customer/shipment (including UPS & FedEx, weights vary for some products). "Some" shipments require fumigation, phytosanitary certificates, as well as other government, taxes and hidden processing charges (corruption fees).
We are looking for a way to bypass, or edit the Payment Option, by stating: "Your order will be charged based on actual cost from the shipping company. Your shipping charges will be determined based on the final weight, destination, as well as other charges if necessary". In the Admin area we would like to input the final cost of shipping when the cost of shipping has been determined at time of shipment. We dont like to overcharge our customers for shipping, and we also dont like to loose money on shipments that were incorrectly estimated, due to unforeseen charges by cargo/shipping companies (sigh). We like to choose to be fair on our shipping policy by obtaining the correct shipping charges for us and our customers, making both parties happy.
I am sure this is an easy implementation for a shipping option, but do not see it as an available option.

debsid wrote: We are looking for a way to bypass, or edit the Payment Option, by stating: "Your order will be charged based on actual cost from the shipping company. Your shipping charges will be determined based on the final weight, destination, as well as other charges if necessary".

You could use any of the shipping methods and set it to be zero shipping. Then go about changing all the wording on the template file email.

In the Admin area we would like to input the final cost of shipping when the cost of shipping has been determined at time of shipment.

then get this extension to enable you to edit the order to include shipping
http://www.opencart.com/index.php?route ... order=DESC

I haven't tried that extension so check it out to see if it'll work for you