eHarmony offers promotional codes and discounts on a regular basis. These codes can come in the form of a monthly special or a year-long discount for purchasing a membership in advance.
A free trial of eHarmony, while it is possible, is a little less structured. While it is not formally labeled a "free trial", the method some users follow resembles a free trial both in cost and duration of use. Full use of the site can be purchased, and as long as it is cancelled within a three day window, a full refund will be credited back to the users account.