From Longman Dictionary of Contemporary Englishtrade down phrasal verbSELLto replace something you own with something cheaper, or buy a cheaper type of thing than before to Many of their customers are trading down to cheaper cigarettes. → trade→ See Verb table
Examples from the Corpus
trade to• Prices steadied and ended the day largely unchanged after November traded down to £677 a tonne, the lowest for 14 years.• Nor is the team likely to trade down to assume a draft position where it could legitimately take Nash.From Longman Business Dictionarytrade down phrasal verb [intransitive]MARKETING to buy cheaper goods that are of poorer qualityConsumers aren’t trading down in quality, but they are cutting costs in other ways. toThe brand’s loyalists increasingly traded down to cheaper cigarettes. → trade→ See Verb table 