Double Time!

Generally speaking, reprint sets have a clear curve. This started with the first modern-era reprint set, 2013's Modern Masters. The time to buy in was after the next set came out and attention had veered away from the reprint set and to the new expansion set, but before more than a year had passed. This is especially true with the cards that have the greatest amount of casual and Commander appeal.
Let’s take a look at the long-long-term graph of Doubling Season, which was a rare seven years ago:

Seems crazy now, but you could get this card for under $20, and even as low as $15, during the six months that followed its printing. However, that was forever ago. Let’s look at the same card from Battlebond, a mere two and a half years ago:

This time, we had the precipitating event of War of the Spark that caused a jump in prices (after all, Doubling Season + planeswalkers = instant ultimates) but those prices didn’t go back down after the spike.
The newest version hasn’t had a chance to sink very low yet, but it’s entirely possible that as a mythic (and there were twice as many of those in Double Masters) with a premium Box Topper edition, this price of $45 is real and is the cheapest it’ll be until the next reprint. If it dodges a reprint in Commander Legends at the end of this year, watch out.
Frankly, though, given the number of decks that this is in, and the number of strategies it makes better, if it is reprinted and goes down to $30 (as an example) then I’d want to buy in at that price. It’ll get back to $50 before too long.
Reprint sets can hold down a popular card’s price, but not forever. Expensive reprints happen because supply was constrained or demand never slowed down for a card. My favorite example of constrained supply comes from True-Name Nemesis

At first, this was $40 all on its own because you could only get one copy at a time. Wizards was content to reprint more than one copy of the Commander deck that it sent out, and it took years for the price to get back to $30... just in time for the Battlebond reprint, which represented a useful number of copies and will keep the price low for another couple of years.
So which are the cards that represent the best deals? I’m looking for Commander playability mainly, as I don’t know when paper events will pick back up. I’m not worried about the number of times a card has been printed, as a high enough level of demand takes care of that nicely. I’d love to find that the Double Masters version is the cheapest, hopefully by a significant amount.
With these criteria in mind:
Jace, the Mind Sculptor

Is it worth an extra $20-$30? All up to you. The DXM version is about $10 cheaper than any other, which is a number I can appreciate. Big Jace is coming off a three-in-three-years run, given Masters 25, Eternal Masters, and now Double Masters. Remember that he was up near $150 before that run started, and while I don’t think he’ll Reach that high again, $100 is quite possible.
Mana Reflection
Austere Command
Land Tax
Blasphemous Act
Phyrexian Metamorph