Fair warning, the following is a bit of a rant regarding the vintage gaming collecting scene using eBay.
As a retro gamer, I am always on the look out for classic consoles to add to my collection. There are very specific consoles not in my collection that I really want, but are a bit difficult to find in my region. So, I turn to ebay. eBay has become a bit of a "hit and miss" these days. Not because eBay is so difficult to use, or find things on. It is due to the individuals selling their old consoles.
If you go through and search the vintage consoles, you will see fairly reasonable prices within the 40 to 60 dollar ranges become slimmer and slimmer. Rarely do you find any lower. Now, this isn't due to a bidding war, but rather the initial price listing!
Sellers are posting their goodies with ofttimes outrageous prices exceeding $100 for systems as common as the Atari 2600 VCS, NES, and others. I have even been finding listings of "For Parts" listed with similar prices. Honestly, this is outrageous. What is worse? These individuals are using terms to snare the uninformed with words like "Rare", or "Limited Edition". This is an obvious ploy to take advantage of the young collectors.
However, I counter this ideology being employed. Collectors searching for these older consoles aren't young kids looking to "experience the golden age of gaming". No, it is individuals like myself. People that grew up on these consoles. People wanting to recapture the enjoyment we experienced in our youth. Generally, most of us that are collecting these older consoles know that these machines are not "rare". Especially when your Atari 2600 "Vader" is listed next to half a dozen others, AND along side DOZENS of various models of Atari 2600 VCS consoles.
Now, when talking about the cartridges, I can understand that bit. There are various levels of availability of games. Using various websites that support the collecting scene will have a listing of all known titles with their rarities listed. This not only includes released titles, but unreleased, and even betas.
eBay has always been a place to quickly and easily ditch your old stuff to people wanting it. However, just because it is "old" doesn't mean it is "rare" or "valuable".