An MSRP of $40 isn't THAT bad for the console... I'd pay it. Keep in mind it will have games built-in. Just because the systems are $20 or less doesn't mean the vintage cartridges are dirt cheap. Sonic & Knuckles itself is about $15 used at the scummier outlets. If you can get Sega to let you have more popular titles then it shouldn't be a problem.

I'd go ahead and try to market it. The damn Yobos sell between $50 and $60 in the used game retailers that carry Yobo stuff and they actually fly off shelves. One outlet near me won't even take trade-ins on the vintage consoles because the Yobos sell better. Another store I know of sells the FC Mobile so they already buy from you.

I'm going to be in contact with my local used retailer, provide them Hyperkin's
info and see if they'd want to order stuff from you. I don't know where they're buying the Yobo stuff, but I'm guessing it's ALL they offer for sale to them.

Now, I'm guessing from the photos that the button above the d-pad is the mode button for the 6-button incompatible games, since the start button was usually above the action buttons.

Just make sure the controllers included with the console have that button.