on the contrary auctions tend to go “really bad” compared to those prices (gyarados BIN 900 → on auction 450), so my question is, what would be a right estimate of this set?
Do these prices make sense to you? would a complete set demand a premium or not? how much would you pay for a complete set with/without the fan club karp?
The FC Karp checks every box for me in terms of rarity, collectability, etc. It's also my personal favorite artwork, so I was more than happy to buy one recently for $7k. Spent over a month looking for a 10 at a lower price before finally finding a willing seller. I'm aware that many on E4 discord think I was stupid to pay that price, and to each his or her own.
The last public sale was via PWCC in late July of last year - when prices are generally depressed across the board due to the summer slowdown - for $5,600. As mentioned, the last few 9s have all sold at $3k or over. In my view, the idea that there can be an established "market value" for an immensely desirable card with gem mint pop of 16 is pretty laughable because it's simply too rare to draw meaningful conclusions from a single data point. Plus, we're all aware that the market has been extremely strong recently, and a six-month price jump from $5,600 to $7k is honestly benign when compared to what other high-end cards have done in the same timeframe.
I’m traveling for work and forgot my crystal ball at home, but I’ll do my best to answer your question. I believe that prices are rising concurrently across many sets because the demand for the quality stuff is outpacing the supply; the inevitable contraction that followed the mad collecting rush after PoGo hysteria has come and gone, the hobby is super strong and new thresholds are being crossed every single day.
The Neo Shinings are obviously exceptional cards - almost universally beloved, have serious cross-generational appeal and very robust sales data, which can make them less scary for new/cautious buyers. Also, the Japanese set is still poised for growth as more and more people become priced out of the more expensive 1st edition English and have to look elsewhere to satiate their completionist desires. I truly can’t imagine what type of market mechanism would result in a precipitous drop for these cards, but I admit I’m biased because Pokemon is life and all that. ; )