Shipping Estimate based on ZIP code only
Is this possible to use only the zip code to give an estimate for shipping on items?
It depends on the shipping methods. Some of carriers require more address information than just the zip code. For example, FedEx requires the zip code and the city. Even then, the estimate will often be higher than the actual cost (which is based on the street address, city, and zip).
You could subscribe to a zip code service and then add code that looks up a city based on the zip code. But that will probably lead to even worse estimates. Many zip codes touch multiple cities and the the shipping cost to each can vary quite a bit. If your code simply picked the first city in the list, the estimate would be wrong quite often.