Does anyone know why the prices would be that much different? For the searches I've done, Google Flights is close to $150 more than what Hipmunk shows. Does Hipmunk maybe just have some sort of promo or lower price that Google Flights can't offer?
EDIT: This curiosity also relates to what "karakal" is asking in their comment: https://news.ycombinator.com/item?id=12736433 - Like is this data just universal or do some services get better deals than others?