I don't have the skill/knowledge or the time to learn how to make encoders.
I had 2 extra KeyWiz Eco2's after obtaining an order from RandyT.
1 was a spare I threw on eBay out of interest and sold for $46 AU. The second Eco2 is on there now (courtesy of a mate who decided he didn't want it any more)

Here's my quick costing on 5 Eco2 solderless units:
$US28 for post
Total $US138.75
At xchange rate of 76 cents:
= $182 Australian
= $36.40 for each unit (including share of postage)
So I made about $10 AU on the one I sold.
If I could get the unit cost down to around $30 AU I'd be happy to sell for about $40 - $45 AU. (This is the solderless Eco2, not the deluxe).
I would assume that if I ordered more in larger batches, economies of scale would ensure more units were available to absorb the postage cost and average price would come down.
But I would have to ensure that me reselling them here in Australia was OK by RandyT and was not against their company policies, contracts here in Australia etc. If RandyT is following this thread, his comments yes/no etc would be appreciated.
Then there is the GST, BAS etc to comply with taxation yada yada yada.