Still got those Megadrive/Genesis carts?

i had a jap import when they had that shortage that played uk games fine (some in japanese mind), the plastic casing was physically different but that was it, iir there was a notch or something that physically prevented states games working on uk and perhaps jap machines that or a country chip like the snes
so will we see a rise in price and shortage of availability of mega drive carts in the 2nd hand section of shops that have retro gaming sections now

those tv versons would have been better if they had 2 pads and a cart port, cos they kinda defeated the whole idea of the console and iir they were around the price that the link said, £30ish
ok the whole thing slapped inside a pad is a great idea, till you see the size of the megadrive shaped psu (or was everything inside that?)