I wonder if the issue has to do with where either you or the seller lives ? I can find hundreds of HID lamps/fixtures/parts listed on eBay as we speak .

@wide-lite 1000, same here when I search for the HID's and certain fixtures... and here soon I plan on utilizing this for my garage a bit more.
Still also finding fluorescent ballasts and lamps easily as well, most for a reasonable price... so this also makes me wonder if it could be due to seller/buyer location.

 That's what I'm thinking .

Yes, the "suggested" lamps are there because the sellers paid to boost the listings.

As for insane prices, tell me: how much does a carbon filament lamp cost? They haven't been produced since the '40s or '50s and they have been banned for a couple years now.

It comes down to simple economics, my friend: supply is low, but demand is also low, the price will remain low. The price would only skyrocket if everyone suddenly decided they
wanted to transition back to MV and such, in which case they would probably start producing them again.

carbon filament lamps were made into the 70s. Maybe even 80s.