In the US, Walmart is still selling the M1 MacBook Air new, for $599 (and has been discounted to $549 or better at times, such as Black Friday).

In general, I don't think it's reasonable to worry that Apple's products aren't thoroughly achieving economies of scale. The less expensive consumer-oriented products are extremely popular, various components are shared across product lines (eg. the same chip being used in Macs and iPads) and across multiple generations (except for the SoC itself, obviously), and Apple rather famously has a well-run supply chain.

From a strategic perspective, it seems likely that Apple's long history of annual iteration on their processors in the iPhone and their now well-established pattern of updating the Mac chips less often but still frequently is part of how Apple's chips have been so successful. Annual(ish) chip updates with small incremental improvements compounds over the years. Compare Apple's past decade of chip progress against Intel's troubled past decade of infrequent technology updates (when you look past the incrementing of the branding), uneven improvements and some outright regressions in important performance metrics.