A $40 Denali was the type of bike my brother and I would get for Christmas. A Denali at regular retail price was something we might dream of getting someday as a hand-me-down.
I rode a pretty crappy bike for many years, starting from the time I was big enough for an adult-sized bike. It was do-able, but not enjoyable. The post above about stamped or pot-metal shifters and brittle plastic was 100% accurate.