Eyeglasses at the eye doctor are expensive. I can buy 10 pairs of glasses online for the same price as one in the doctors office.
When you get a checkup, ask for your prescription and the measurements for your glasses. This includes the pupillary distance (PD). This is important because the vision will look distorted if this is not correct. Also, measure your current glasses and use these measurements as a comparison for the glasses on the web.
I bought glasses from a few different websites and had the best success with Firmoo.com. My glasses arrived after about a week and it cost about $50 for two pairs. Firmoo has some coupon codes listed here.