I made this exact mistake when the Switch OLED came out. I got caught up in hype, I bought the new one, and slowly it dawned on me that I just spent 300 extra dollars for exactly the same machine I already had, and a screen that, as good as it was, was NOT worth that 300 dollars.
If you don’t own a Steam deck, then go nuts! Do what you want.
If you already own a Steam Deck, you already own everything you actually wanted a Steam deck for. An OLED screen is not going to make the games you already play somehow magically better. You’re fine. Chill out
I think you would be lucky to get $300 or $400 for the SD depending on the model. I expect a lot of people are going to sell and drive down the price down. The 1TB is going to cost about $700 when you factor tax. So $350 upgrade cost. That’s almost a new PS5. Great for someone who doesn’t have a deck yet. Not great for existing deck owners who want to upgrade to the 1TB model.