It’s interesting to say the least. I can’t speak for PSA or graded sales as I don’t pay attention to those, but I can at least tell you what I know of English Raw sales as I’ve passively observed them over the years. So take what I say with a grain of salt.
1st Edition Base Gyarados has been all over the place this year. I saw copies selling for between $700~$900 during the summer of 2020 when you used to be able to buy a decent copy for $200~$300 back in the day. All of a sudden those prices have fallen at the turn of 2021 and are now finding cards once again for $200~$400 range depending on condition with a few outliers (can’t speak for the difference between Thick & Thin stamp as I already had my copies and didn’t care to look into that)
1st Edition Shining Gyarados had a similar rise and fall - You could buy copies for around $200~$300 for a number of years but all of a sudden, at the start of Covid last year, the average price rose to around $800~$900, fell to around $400 at the end of the summer, and has been on the rise again since the winter around $600~$900 per card.
Base Set Gyarados holds itself as the standard - time immortal - and will forever hold a special place in history. It has all the facets of what made Base Set iconic for it’s Holo rares - perfectly framed Pokemon, holo background, that classic S-shape that everyone recognizes. Everyone has seen this card. It’s wonderful, incredible, beautiful, cover girl.
But Shining Gyarados? Shining Gyarados changed the game for card art.
Prior to it’s release, Gyarados cards had stock art cookie cutter features (outside of Dark Gyarados) with Misty’s and Giovanni’s Gyarados featuring an image that was released on hundreds, if not THOUSANDS of products. Everyone is familiar with the images and only a select few could truly appreciate the incredibly weird and Japanese influences of Himeno’s Dark Gyarados from the Rocket series.
Then comes Shining Gyarados:
Shining Gyarados is legendary. If I had the funds, I’d have a whole binder set of it. Gyarados was the FIRST ever Pokemon to be released as Shiny in the Heart/Gold series and the first ever Pokemon (alongside Magikarp) to be featured as Shiny in the TCG. It shows a narrative, an incredible scene between ferocious beast and the fool that is that poor, poor, poor fisherman facing a Leviathan caught in the middle of it’s rage. People loved Charizard for it’s orange dragon qualities, but everyone swoons for this red celestial dragon. So much so that it has become iconic with the Neo set, Japanese products feature it often in Gen 2 memorabilia, and is the only version of Gyarados to be featured as a Mega in the TCG (we still don’t have a regular Blue Mega Gyarados yet).
I know people on IG who have binder sets of this Pokemon Card, PSA 1-10 collections, and buy endless copies and most of them aren’t even self-described Gyarados collectors. You’ll see this card mentioned time and time again in threads asking for “best” or “favorite” cards.
And rarity aside, it comes down to supply and demand - and I believe the demand for 1st Edition Shining Gyarados seems to outshine 1st Edition Base (as some have already highlighted above). And if you pay attention to proxy-card sales, I’ve only seen a handful of 1st Edition Base proxies grabbed up - but people have been consistently pumping out and buying 1st Edition Shining Gyarados proxies for 2 straight months now - the bastards.
1st Edition Base Gyarados is Immortal. But 1st Edition Shining Gyarados is downright Legendary.
In either case, @rainbowneosking, I wish you luck on finding one! It’s one of my top 3 for a reason.