It is true that major investments like new factories might conceivably become cheaper but this also ignores opportunity cost - in the same way, with inflation, new factories are more likely to become more expensive, so it's logical to think that in inflationary times, the countryside will be dotted with idle factories built as a hedge. This doesn't happen because of a variety of factors, not the least of which is that people make investments because they expect to see a big margin difference between keeping the cash and having that investment make cash for them. You don't built a new factory because you think you'll make 3% more than bank interest, you do it because you think you'll make 20-50% return on the cash.
The deflationary spiral postponed purchases explanation is a bit like the efficient market hypotheses - plausible sounding but ultimately and empirically not true in practice.
The iPhone 6 just had record sales so empirically there are other factors for consumer purchases that are stronger than the "waiting for items to be cheaper" factor.