My 8 year old likes base Carcassone but is of the opinion that the game is overcomplicated by adding in the first two expansions.
I've been browsing through Amazon looking for boardgame bargains too, and the following all seem to be below usual price (apart from the Carcassonne expansion, I don't own and have never played any of them myself):
Carcassonne Traders and Builders £13.50
Sun Tzu £11.99 (BGG rating 6.4)
Heroes £10.98 (BGG 5.7)
Ca$h 'n guns 2e £20.23 (BGG 6.9)
7 Wonders £26 (BGG 7.8)
Isle of Skye £23.99 (lowest price ever; BGG 7.2 - this just won the 2016 Kennerspiel des Jahres)
Takenoko, the cutesy panda game, briefly dropped to its lowest ever Amazon price yesterday, so might be worth watching.