I'll just say that this is really neat... but it would be even neater if someone offered up parts kits (or even built unit) for convenience and economy of scale.
For my original version, at first I offered just bare PCBs and a BOM from DigiKey and/or Mouser. PCBs were $10, parts totaled about $10 or so.
I think I sold about 25 bare PCBs total. Still have about 20 bare boards left, no one wants one anymore.
Later I offered a kit of all parts for $15 (I added $5 for my time sourcing and sorting parts into kits).
I think I sold about 15 full kits of parts (PCB, all parts, microSD adapter) in about 2 years time. There is one straggler kit left.
It takes about 2hrs of assembly and soldering to assemble the board (maybe 1hr if you really push it and are a competent tech).
As to economy of scale, there really is none. The market is not that big.
For preassembled versions now, I would redo the design in surface mount and let a professional small volume assembly house do the grunt work.
Probably all they could not do is the Arduino shield headers, probably still need thru hole and hand assembly.
In my selling of boards at $10 (cost $8), parts kits at $15 (cost $10), and Sparkfun microSD adapter at $5 (cost $4.50) plus my time I think I maybe broke even. Maybe.
A fully assembled professional version would probably need to go in the $50 to $75 range to make it worthwhile (ie at least break even and not a money loser).
But at this point I question the size of the remaining market. The availability of RX8E/RX28, RX211, RXV21 interface cards is probably the more critical factor.