MTGFinance at it's most mediocre!
Dragon Arch {5}
Artifact
{2}, {T}: You may put a multicolored creature card from your hand onto the battlefield.
This one might seem a bit odd as it is an uncommon, and not on the reserve list, but hear me out.
This card in commander is generally a really good card. Especially if you pair it in a deck that focuses heavily on fast ramp of your mana pool.
While if you check edhrec it isn't in that many decks.
I think that has more to do with the fact that not many people know about it. There are still a trove of cards from Invasion to Scourge that haven't been sourced yet for commander.
The biggest reason that it hits one of my quick picks is that it is an old school foil that when commander people realize it's potential will want it in foil.
Long Term Price Perdiction?
It will probably end up in the $40–$50 range long term.