I feel like this is a rare case where you are one of the only ones with that product. Meaning, you alone can set the price.
With that said, with the right buyer, it can go for $200+ USD. But this is a very hard sell.
The only consumer who would want a Wacom 480 are osu! players. Most of osu! players aren't mega-rich, therefore they would look for alternatives tablets or even consider a used 480.
Collectors also won't buy it because it's not the limited/special edition.
That's your first problem. Your second problem is selling the item. Where ever you are selling the item, you better have a good rating or otherwise no one would buy from you, or believe that you somehow have an unopened product.
But if give a go, it might an easy sell. It's smarter to set a higher price first, then wait... then lower the price. If used is around $100 to $150 like you said, then price it at $300 seems logical.
When selling limited goods, the name of the game is to be patient, eventually somebody will come along and buy it even it the product is priced high. Best of luck.