Having game pieces be unobtainable is bad, and if you cant afford to pick up a Wheel, dont feel bad about proxying one
Some might argue that Urzas Saga should be on the list, and while it can be a nice way to grab Colossus Hammer, Sol Ring or the aforementioned Masterwork of Ingenuity, its also a lot pricier than The Mycosynth Gardens
Where to Play Mangara
You can distinguish a proxy and the genuine MTG card by looking out for various factors such as the cardstock texture, does it feel like your existing MTG cards
Id buy these for the new cards and the reprint value, but I wouldnt stockpile them as an investment
Use Blood Tokens and Fable of the Mirror Breaker to get Tree of Perdition in the graveyard, and use Agathas Soul Cauldron to exile it, granting all of your creatures with +1/+1 counters the ability to swap life totals