downmarket vs low-quality

downmarket

adj

Of, or relating to the less prestigious sector of the market.
Designed for low-income consumers.

adv

Towards the less prestigious sector of the market.

verb

To make or become downmarket.

low-quality

adj

Of poor quality; inferior.

How often have the words downmarket and low-quality occurred in a corpus of books? (source: Google Ngram Viewer )