Last time I checked sellers do not owe it to you to sell you video games at a price you want. You also don't owe it to the seller to buy it at the price they asked. I am not understanding the issue.
Also its is a bit hypocritical. People seems to think its only fair for them to demand a lower price from a seller, but if the seller asks for a higher price than the buyer want to pay then somehow the seller is a greedy . However you could technically say the same thing about the buyer demanding a lower price, they are also being greedy. This is the eternal struggle of the free market and greed is the biggest driver. Sellers want to sell something for the highest price they can, buyers want to buy it for the lowest price they can. If no compromise can be met then both the seller and buyer walk away empty handed. If the seller never compromises on price and can't sell their goods then they will go out of business, that's their problem.
Sure there are cases where someone can attempt to corner the market on rare items, but this is a huge risk they are taking. If I went and bought all the Nintendo World Championships I could. Basically just offered a ton of money to everyone known to have one so I basically corner the market on them. What if no one buys them at the ridiculous asking price I would have to ask to make it worth my while? Well I am royally screwed most likely. Unless I am just that rich where that money means nothing to me and if that's the case why the hell am I buying NWC to re-sell? Seems like a pretty piss-poor strategy to make money I don't even really need.
Right now the retro gaming market is sky high, no doubt about that. However this happens with any kind of collector's market, prices rise and fall. These prices will eventually fall. If the prices are too high for you right now then I would just wait. Give it a few years and try again.