It's usually not necessary to physically visit a shipper in order to
calculate shipping costs. Accurately measure the length, width, and
height, and the weight and value (if there are duties). Call or
contact the shipper and provide this information as well as the
If the shipper can't provide costs with that information, they're not
much of a shipper. Even if there are packing costs involved, they
should be able to estimate accurately.
Here in the US you can very easily do this yourself using the web sites
of UPS, FedEx and U.S. Postal Service (and others; these are the services
that are common in my area).