歓心を買う[kanshinwokau] to win favour
競争売買[kyousoubaibai] auction
故買[kobai] buying stolen goods
購買[koubai] procurement
購買力[koubairyoku] buying power

思惑買い[omowakugai] speculative buying
衝動買い[shoudougai] impulsive buying
人身売買[jinshinbaibai] slave trade
人買い[hitokai] slave traffic
青田買い[aotagai] speculatively buying a rice harvest, while the fields are still green

ゴミ集積場[gomishuusekijou] village garbage collection point
英字集合[eijishuugou] alphabetic character set
家集[kashuu] poet's poetical works
歌集[kashuu] anthology
画集[gashuu] book of paintings in print

会集[kaishuu] audience
解集合[kaishuugou] set of solutions
寄集め[yoseatsume] mish-mash
寄せ集める[yoseatsumeru] to put together
寄り集まる[yoriatsumaru] to gather together