Man game collecting has changed. You used to be able to find Genesis AV cables for $10-$20.
Sure if you check online and buy them seperately you can find og 1st party cables boxed for not to high of a price although still pretty tricky to find if you'd ask me. even years ago they where pretty uncommon. I'll say this I've personally seen more Gamecube component cables than sega 16 bit av cables
1st party av cables functionality wise are just useless. It's just a niche collectors thing when it's cib considering 3rd party av is fine and av in general is more of an entry lvl option as reasons why the price is quite low.
I have never come across them in sets always those damm antenna cables and the occasional low quality 3rd party scart the quality of the set doesn't matter. Sega just hated av cables it seems. Even with the nes you can get official av cables since it was usually included when you bought them.
Not expensive at all, but considering how you pretty much never see them in sets it's a rarity. still 3rd party av cables are only a couple $ and work just aswell. but it ain't the best option anyway. AV is just a quick plug and play option withouth much hassle compared to the better options. Probably only very few people that bought av cables for the system back in the day considering you had to buy them seperately.