Hello, I have read all your requirements and completely understood that you are looking for an expert website developer to install a plugin to adjust the shipping cost of your packages depending on the postal code, weight & dimensions. I assure you I can make changes exactly as per your requirements within 24 to 48 hours in your budget. I am a professional developer having more than 7 years of experience in PHP, CSS & HTML. A perk of hiring me is that I will give you 24/7 support even after the project will be completed. Thank you.