cheap has 21 distinct synonyms spread across 4 of its 4 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is expensive.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
relatively low in price or charging low prices
“it would have been cheap at twice the price”
Synonyms, antonyms and the broader and narrower relations for cheap come from Princeton University’s WordNet. Full sources and licences.