locally obtained electronics could be bought locally and soldered on. Most of the cost of these boards is the manual soldering of the parts onto the boards, not the boards them selves. Let the end user do it if he can, just ship him the boards. Those that can't solder and/or find the bits can buy the pre-assembled ones.
There are a few catches about this. First, "locally obtained electronics"- nope. It took me half a year to find a supplier for GBA slots, and they required me to buy 1000+ of them, and not exactly for cheap. Second, "let the user do the soldering" - another nope. A Retrode user recently tried to gather folks for a group order of PCBs and parts, and over several months in various forums he didn't manage to find a single person to join in. The boards are cheap and as easy to obtain as anything, that's right. Unless you're taking less than 50; because then you may have difficulties finding someone who does the gold plating, chamfering, nonstandard board thickness, etc at a reasonable price.
Sometime around the release the Retrode2, I will try to offer as wide a selection of plug-ins as possible, pre-assembled, in Genesis cart shells and at a reasonable price. Until then, anyone can build their own from "not-easy-to-obtain" kits (ever considered asking me?)
Cheers,
Matthias