The 3M Kit is a simplified version of what /u/bran_donger posted, but his might be even cheaper. I found that the kit served me well, but you will have to do it every summer regardless if you live in a sunny area.

i used this one:

https://www.amazon.com/3M-39084-Headlight-Restoration-Kit/dp/B01MZWNT93/ref=sr_1_6?ie=UTF8&qid=1535047593&sr=8-6&keywords=3m+headlight+restoration+kit&dpID=51J-qVf2PrL&preST=_SX300_QL70_&dpSrc=srch

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but there's also a version with an attachment for your drill which is probably easier but both are simple and would only take an hour at best.