Dream is related to Happy. Happy is related to Pleased. Pleased is a synonym of Glad. Glad is the opposite of Disappointed. 
Best is related to Buy. Buy is related to Involved. 
Dream <--RelatedTo--> Happy <--RelatedTo--> Pleased <--Synonym--> Glad <--Antonym--> Disappointed 
Best <--RelatedTo--> Buy <--RelatedTo--> Involved 