All of our prescription glasses are priced including standard lenses.
Our standard lenses are the same as those provided by the vast majority of opticians and are made of a lightweight plastic material known as CR39. For more information there is a Wikipedia page detailing the properties of this material and why it became the popular choice for making scratch resistant lenses.

Varifocals, or Progressive Addition Lenses incorporate distance, intermediate and reading prescriptions on one lens. The prescription changes gradually from clear distance vision at the top, clear reading vision at the bottom and an area in between that should serve for intermediate use.

Your PD may be noted on your prescription. The measurement needed is that between the pupils when the eyes are gazing into the distance.