I would do Sheetrock.
Try this link for a do it yourself, anyone here will tell you it's worth your time to learn. And easy to do.
This will be the least expensive for you to do yourself.
Or, Compare other 1/2 inch materials at the lumberyard for prices. Stay away from 1/4 inch paneling in a garage. The fluctuations of temperature over time warps it , and this really looks bad.