Jennifer Lopez has 10 million reasons her summer will be better than yours ... she just dropped a boatload of cash on a massive Hamptons estate ... just in time for beach season. J.Lo closed the deal this week with real estate guru Susan Breitenbach of the Corcoran Group ... scooping up a chic 8,500-square-foot mansion near Mecox Bay for $9.95 million. The pad is obviously amazing , t's in the Hamptons, duh -- with 8 bedrooms, 7.5 baths, 3 acres of land, a theater, pool, spa, sauna, steam room, pretty much standard rich people house stuff. And get this, we're told Jennifer bought the place as a summer hang out spot. The land baroness already owns a mansion in Hidden Hills, CA and two homes in NY.Baller.