Zenni optical has the largest selection of frames and lenses. As to the lenses, they have single vision lenses, bifocal lenses, progressive lenses and reading lenses.
1.50 single vision and 1.57 mid-index are free. As to the 1.53 trivex impact resistant, it costs $29.95. But it costs $9 to get 1.59 polycarbonate impact resistant lenses. The 1.61 high index lens is $19.95 and $35.95 for 1.67 high index lenses.
When it comes to bifocal lenses, zenni optical has two kind of lenses, 1.50 bifocal with line and 1.61 bifocal with line. The 1.50 bifocal with line is $17 and $46 for 1.61 bifocal with line.