Indiana is a big places, where you to buy eyeglasses depend on where you live. You can buy prescription glasses from the nearest glasses stores to your house. If the glasses in local shop are expensive, you can search it online. There are many online glasses shop that provide affordable prescription glasses only if you tell them your prescription. As far as i know, prescription glasses i at firmoo.com are cheap, and they also offer free glasses. So, you an browse out yourself.
To be honest, prescription glasses sold in the local optical store are usually expensive. If you want to get affordable glasses, you can get them online. Glasses online are much cheaper than that in the real store. There are so many online optical stores offering prescription glasses with affordable price. However, before you order prescription eyeglasses online, you should go to see an eye doctor to have an eye exam so that you can get your prescription which is required when you order glasses online.