Gary, from late 1979 through Spring 1981, I worked for American Radio Corp., based in Aurora, CO. I designed the exact device you're asking for. It was built to interface with the then, very popular Kenwood TR-2200 handheld. You might not be familiar with the unit, but the interface connections were on the side, not the bottom like the similar Motorola unit aimed at the public service market.
The tray the radio laid on had a special 3M tape developed for the purpose. The power amp was based around a CRC VHF FET (Please note, this was (1979), and put out 25 watts. The audio amp was a full 5 watts RMS. It was called the ARC220.
The first production run was 25 units. I still have one production unit, and the original prototype in my possession.
Kenwood had sold nearly 10,000 of them, and you'd think you could sell a few of the units. All told, HRO sold 18, and the rest were almost given away. The investment was nearly $20,000 in 1979 dollars, and with an MSRP of $129, it would have taken hundreds to recoup the investment.
At about the same time, Icom introduced their new handheld. It was half the size, half the weight, put out nearly twice the power, and cost less. In order to adapt the unit would have cost another $8,000 or so.
The only amateur product ARC built that went anywhere was the deviation meter. We sold about 100 of those at $49 each MSRP. I don't remember how much the design cost was, but I'm sure it was never recouped.
There are companies making money on the amateur nitch market (actually amateur radio is already a nitch market). MFJ is a very good example. However, in order to compete, the quality has to be on the dull edge (certainly not cutting edge). Or, the selling price has to be very high.
As for a universal interface; Motorola tried to do just that. At about the same time, Icom, Midland, Uniden, and a few others started after the public service market. After Harris bought GE two-way radio division, they closed it. They weren't about to buy the market like had been GE doing.
As Lon alluded to, there is much more to bringing a product to the mass market than meets the common eye. Part of the misconception comes from applying an MFJ-style nitch marketing technique, to mass marketing. With some apologies to Samuel Clemens, "The twain shall never meet".
Alan, KØBG
www.k0bg.com