Hmm, what I can tell you is that a 256 GB Samsung SD card from Best Buy is $200, so if this is legit, it's an insane markdown. If this were Amazon I could speak more intelligently, but I don't really know how things work on eBay. Definitely seems too good to be true. Then again, less than $30 isn't much of a risk, so maybe go for it and you'll be pleasantly surprised? FWIW, I searched for "256 GB SD card" on Google and found this very same card on eBay for $60:
https://forums.androidcentral.com/e...2691476036%3Fchn%3Dps%26fl%3Da&token=bnDY8suf
Keep in mind also that not all SD cards are created equal. You could get a legit 256 GB SD card from Best Buy, Target, Walmart, etc. for a lot less than $200, but it won't be as fast as the Samsung one. If you're just storing photos on it it's probably not a big deal. But if you're going to put your apps on the card, this could become a problem because they won't be able to transfer data into RAM quite as quickly, and you'll notice some lag. It's possible that recording or viewing those snazzy new super slo-mo videos on the S9/S9+ might also be slower.
Apologies for the unsolicited advice here. But what you might consider is getting a Samsung 64GB SD card from Best Buy for just $30. It'll give you great read/write speeds, and should have all the storage you need. For what it's worth, I'm an average smartphone photographer, and I have a 256 GB card from the Note 7 promo. I use my SD card to store all the photos and videos I've ever taken with my Note 7, S7 Edge, S8+, and Note 8, as well as the photos I take with my drone, and I'm only at 34 GB. I grant that the S9 is going to have a great camera which will result in much heavier usage, but unless you're a prolific photo-taker I think the 64 GB Samsung card may be your best bet.