It's funny how custom In-The-Ear instruments cause people to think one of two ways about pricing. I have had people come to me and expect the smallest, most invisible instrument to be the most expensive, and at the same time, have had people who think the most powerful, most filling instrument should be the most expensive. Which is it? Is someone who waited a little too long going to be automatically footing an $8,000-$10,000 bill for a larger Full Shell? Or is the individual who works as a realtor, group speaker or clergyman going to get stuck with that bill for the invisible IIC?
If an Audiologist or Hearing Aid Dispenser ever relates size to price in this day and age, RUN!!!!!
Originally, before programmable hearing aids were ever an option, size did correspond to pricing. When ITE instruments came out in the 1960s, there were pricey in comparison to transistor-powered body aids and behind the ear product. Analog technologies sometimes required size for a decent bass frequency response. Here are a couple ITE designs from the 1960s.
At that time, when ITCs, CICs and IICs were just a dream, circuitry did have to fit in the shell, so the theory that "More Power = More Price" does have some truth behind it.
When it comes to the idea that smaller technology is more expensive, there is truth behind this theory too. Many times, smaller and more discreet technology is more expensive than the bulkier technology. This can be true with braces and glasses. To this day, many chains of hearing aid brands still upcharge for an IIC, which is the smallest, most invisible hearing aid available on the current market. You may be told that this is due to the small size, but it's often due to states requiring a class be taken before extra-deep impressions are allowed to be shot, limiting the providers and price points available for IICs. In these cases, a CIC is only a hair larger and can be made in dark, well-contoured colors.
In today's market, when debating over a custom made instrument, the price should only be dependent on the technology inside your custom instrument. Technology has gotten so small, and the difference between a standard speaker and a power speaker is minuscule. Look at the end of a receiver of a Receiver in the Ear instrument. That tiny square box is your speaker. These are the same speakers that are inside the shell of your custom instrument.
That being said, there are still differences between modern IICs and modern ITEs in function. Certain technologies still do not fit in IICs, such as Bluetooth or Telecoils. On top of that, IICs generally have no wind shields available, but that is less due to size and more due to the IIC fitting so far in the ear as to not be disturbed by wind, but may still not be the idea choice for someone in the wind constantly, like a landscaper, fisherman, or motorcyclist.
The choice of custom instrument size should be a matter of your low-frequency prescription 1000Hz and under, your audiologist or hearing aid dispenser's recommendation, and quite simply, what you are most comfortable wearing. If you decide on top-of-the-line custom hearing aids, it should be because you will be using it in many challenging acoustic environments. If you are ever pushed into an uncomfortable price point on the basis of reducing or augmenting the size of your custom instrument, once again, RUN!!!!!