There is indeed quite a bit of truth to that statement. The cost of additional components required to implement PCM in a transmitter and receiver is probably less than US$5 in manufacturing quantities.

There is however, the additional cost of developing the software that must be amortized over the anticipated sales volume -- but even that's going to be no more than $30-$40 per unit.

With PPM receivers selling for around $50 and PCM ones selling for at least twice that, I suspect that manufacturers are pricing their gear on a "what the market will bear" basis rather than a "cost-plus" one.

However, I predict (and it's a pretty safe prediction) that PPM will eventually go the way of AM and represent a very small percentage of total radio sales.