@TeeSea - The gold version was available when the world was first released. You are correct that no discount is given if you already own the Standard version. Discounts for content already owned are only given for certain sets and compilations with the Complete Your Set discount (CYS). None of the worlds are eligible for the CYS discount.
I would like to know why you now want the gold version. The difference in content between the standard and gold versions is that the gold version also includes the Boardwalk attire set and 1900 points. So your $35 will only get you the simpoints (As you wrote, you can buy 2000 points for $20 from Origin) and a set with 5 outfits.
The difference in cost between the standard and gold versions is $15. So, the 1900 simpoints essentially cost $15 compared to $20 for 2000 points with Boardwalk attire thrown in.
The 1900 simpoints were offered with the recommendation to purchase The Boardwalk venue which was created to go with Roaring Heights. The regular price of The Boardwalk is 1900 points. However, The Boardwalk is offered on the Daily Deal. It is offered twice on the Daily Deal list; deals # 694 and # 890. Deal 694 is offered at 49% off for 969 points. From the
DD spreadsheet, deal 694 is next scheduled to be offered January 29, 2022 at 4:31 AM UTC.
Back when the world was released, I purchased the standard edition as I did not want the clothing set. I waited to use simpoints to buy The Boardwalk when it went on sale.
Did you want the gold edition because of the attire set? The only way to get the set of 5 items is to get the gold edition. Not worth it in my opinion.
If you wanted the 1900 simpoints for the Boardwalk venue, as you wrote buy the simpoints directly from Origin for $20. Buy the Boardwalk on sale when it comes up on the Daily deal for 969 points.
I hope that helps.