Shipping within the U.S. is free for many products. See the list of products here - or, when viewing a collection of products, use the "filter by" pull-down box and select "free shipping" (see below). The product description may also note when shipping is free.
How to filter on products that have Free Shipping
Shipping Rates are listed by manufacturer/brand in the chart below. You can find the manufacturer/brand of a product on the product page above the product's title on the upper right (see below).
How to Find the Manufacturer of a Product
The following example pic shows the manufacturer/brand Lybethras circled in red.
Shipping Rates by Manufacturer