Direct from Origins. Looks to be the lowest historical price to me.
https://www.origin.com/en-us/store/buy/75448/pc-download/base-game/standard-edition?utm_source=affiliate&utm_medium=affiliate&utm_campaign=origin-aff-us-ls-aff&sourceid=Origin_AFF_LS315&c=cVR20kC0FGg&LSsiteID=cVR20kC0FGg-ANx6SGxoy_FhDgtuNvjU3Q
Promo: BRAZIL2014
https://www.origin.com/en-us/store/buy/75448/pc-download/base-game/standard-edition?utm_source=affiliate&utm_medium=affiliate&utm_campaign=origin-aff-us-ls-aff&sourceid=Origin_AFF_LS315&c=cVR20kC0FGg&LSsiteID=cVR20kC0FGg-ANx6SGxoy_FhDgtuNvjU3Q
Promo: BRAZIL2014