At least NEC/TTi didn't charge extra for games on average and in some cases way more for incorporated hardware, cart size, genre, etc. I don't know what everything retailed for in the U.S., but everywhere I went regular Genesis and SNES games were $10+ more than Turbo games and you could buy a TurboChip or CD gane + Tap + Pad all for the price of either Chrono Trigger or Phantasy Star IV. Turbo games plus Turbo CD/Booster/Tap hardware actually cost me the same as or less than Genesis/SNES games plus hardware in the long run.
NEC/TTi never released Turbo versions of U-Force, NES Max, light guns, power pad, Activator, roller ball controller, left handed stick shift style joy stick, 3D glasses, power glove, etc and we actually got games that alone made a Tap a worthwhile investment. Sega and Nintendo knew full well that they were selling snake oil to kids with useless crap like the Activator and Power Glove. At least the Tap and even Boosters had a practical use.
Turbo/Duo Pads come with built-in Turbo switches. Sega and Nintendo made you buy entire new controllers at a premium just for rapid fire. The Super CD card cost at least half as much as the 32X and was supported with better software. You could buyva Turbo-CD plus System 3 card tor tge price of the 32X. The TurboDuo cost as much as the Sega-CD add-on alone and was supported by better software.
The TurboDuo required a Tap for 2+ players, but it also came with Ys I & II, Gate of Thunder, Bonk's Adventure, Bonk's Revenge, Ninja Spirit and Bomberman -which alone justified the purchase of the DuoTap.
I never got composite out if a Genesis until I bought a CDX and even then, I had to spend the price of a Turbo Booster to buy a model 2 Genesis RF switch, just to he able to play it on the average TV set.
They could have even created a new format for Turbo Express games, perhaps as simple as leaving them PCE region and forced people to buy entire new games like Sega did with the Game Gear. But they didn't.
If Nec/TTi were scheming to make money through trickery, then they were the least bad of the three 16-bit console makers.
I wrote TTi a letter telling them, among other things, that RPG was my favorite genre. They sent me a brand new RPG and a t-shirt. Sega and Nintendo coukdn't be bothered to even write back. When I sent my TG-16 in to be repaired, NEC sent me back a new one with KC, a TurboPad, all the hookups and docs.