Optimizing parts, vendors, and process when planning to scale for production is no easy task. This years Hackaday prize is a good exercise for me as I've never looked at any project as a potential commercial project, only as a prototype as a hobbyist.
I've come up with some numbers to get an idea of my cost per unit when I would be ordering parts for 100 units. This certainly won't be a final BOM, and some estimations are made, but will give me some kind of idea what the material costs would be.
If I were to order parts to make another unit I would be spending around $35-$40 CAD. If I were to order parts for 100 units I would be spending around $15-$20 CAD per coaster. The most expensive parts are the supercap and the wireless charging coils and circuitry, making up nearly half of the total cost. Much more research would need to be done into these parts in order to find the best prices.
If I were to make a second prototype the same as the first, there would be about 2 hours of labour involved. This includes hand soldering SMD components, starting 3D prints, pouring resin and clearing bubbles (and light monitoring), and assembling charging base.
Significant time would be saved by:
-using a reflow oven rather than hand soldering all SMD devices (or even using a 3rd party PCB service to solder most of the components during manufacturing).
-relying less on 3D printed parts, and more towards professionally moulded enclosures.
-doing the processes with several units at once rather than doing one to completion.
If brought this to market, a sticker price for this product could possibly be somewhere between $30-$40 CAD with the numbers I have currently.