A typical e-commerce sight is rife with buttons and links such as 'Buy it Now', 'Add to Cart', 'Select', and 'Delete' etc. We call these labels ambigious labels because the label does not explicitly call out the item, or noun, that it refers to.
Use clipped text to ensure labels are unambiguous to AT:
<a href="http://www.ebay.com/cart/add">Add to Cart<span class="clipped"> - iPhone 6, 32GB</span></a><button>Place Bid<span class="clipped"> - iPhone 6, 32GB</span></button>
Clipped text remains hidden to sighted users but visible to AT. Please refer to the Utilities page for more information on the clipped class.
NOTE: An ambiguous label is not an anti-pattern for sighted users. Sighted users gather context from visual surroundings.