I would estimate my Eeveelution collection of ~900 cards is close in value to an Umbreon PLAY gold star card. There is no way I would ever trade my entire collection for that one card, which is my holy grail card I want.
Way back I considered trading my entire collection for a Mint TMB No.3
In the end I got the better deal through staying diversified and keeping my collection. Nowadays I wouldnāt consider trading everything for one card, not even for a second.
I have a lot of graded cards I could rid of, but my most valuable collection is my binder from my own childhood. Itās full of severely played 1st edition and shadowless base set. Never getting rid of it for a single card
If thereās a stipulation that you canāt resell the card, then there definitely isnāt a single card Iād trade my collection for. But if thereās not that stipulation, then Iād happily trade my collection for a Honus Wagner ā and then immediately sell it and rebuy all of the items in my collection lol.
Iām sort of lucky in that the most valuable cards in the hobby arenāt ones Iām attached to at all. While I appreciate cards like Pikachu Illustrator or 1st Ed. Base Charizard, I just donāt have a particular interest in them. There are significantly cheaper cards that Iād much rather own (if, of course, thereās the stipulation that you canāt resell the card).
I wouldnāt do it - my collection is completely based off the idea of having one of every official version of Gyarados - having only one card is an absurd choice to me.
But if I HAD to and it HAD to be for another card - itād have to be a one off card that doesnāt exist. Like a rendition of a few Magikarp attempting to jump over a Chinese traditional conception of a Dragon Gate with a regular Gyarados and Shining Gyarados in the clouds above. The card art would be more traditional - much in the same way the Postal Promos are depicted.
Since Iām mainly a Japanese sealed collector, Iām gonna take the liberty of changing āone cardā to āone sealed itemā. And if thatās the case, then conceivably, the top sealed item would be a confirmed no rarity short pack base set box.
Illustrator or one of the OG pika trophies and then Iād slowly buy back my old collection. My ultimate goal (well dream) is all the oldback holo arts besides the ones with player pictures on them.
If there was a stipulation I couldnāt buy any new cards then I wouldnāt trade for anything. There isnāt a single card Iād rather have than my whole collection.