First, I'm not a Kadee user, so I wouldn't purchase these.
Second, I thought one of the big points of Kadees were that they were body-mounted and not truck-mounted?
Third, how would you ever account for a truck design that fits all the different ride heights, bolster designs, and mounting methods for existing rolling stock from different manufacturers? There's not a truck that can come close to doing that now, with or without Kadee couplers.
Fourth, how would you "mass produce" all the different truck styles -- friction bearing, roller bearing, leaf spring, etc. -- that people would want?
What you're asking is simple, but the reality you're proposing is at least $300k investment in design, tooling, marketing and inventory to get off the ground. The market would have to be gigantic to get anywhere near the "affordable" price you propose.
TRW