Whatever the prices for the PS5 and PS5 DE will be, I think they will either be 100$ apart, or they cost the same. Why? Because a fifty dollar difference doesn't really mean much, at least not as long as the first number of both prices is the same (499 vs 449, or 599 vs 549). There's a reason why most consoles have historically launched at prices that ended with 99. Psychologically a fifty dollar difference would only start to have an impact when we're talking about lower overall prices, like 299 vs 249, or 199 vs 149.
But for anything over 400$, a fifty dollar difference doesn't really do much, unless the first number changes, like with 549 vs 499, or 449 vs 399. Since 599 isn't a mass market price in the long term (and 549 wouldn't be seen as much better), the standard edition will most likely come at 499, just like most expected, since 449 wouldn't be perceived as much of a difference compared to the XSX price of 499. This in turn means that the DE comes either at 399, or it costs the same as the regular edition (maybe it gets bundled with a game and a year of PS Plus or something).
That's why I think those prediction of 449$ or 549$ for either model don't make much sense. Imo the numbers we're looking for are either 399, 499, or 599.