Best is related to Ideal. Ideal is related to Supreme. 
Wealthy is derived from Wealth. Wealthy is similar to Rich. Rich is similar to Valuable. Valuable is the opposite of Cheap. 
Best <--RelatedTo--> Ideal <--RelatedTo--> Supreme 
Wealth <--DerivedFrom-- Wealthy <--SimilarTo--> Rich <--SimilarTo--> Valuable <--Antonym--> Cheap 