Collecting the full set is going to be difficult for a lot of people and despite the excitement of opening packs, the cheapest and most efficient way to catch them all is going to be to purchase singles of the ones you need or to trade for them with your friends
Gix, Yawgmoth Praetor, Bladewhip Transmogrant and Ashnod, Flesh Machinist fill out the curve well
Forever War: The product page for Judgement Force tells of how Adreus and Tiras battled endlessly against each other for two years (ever since their release in Generation Force ), until Armades decided to step in and stop the fighting between his brothers
So long as your deck has an artifact theme, you wont need to worry about paying Engines activated costs either, since Unwinding Clock will also untap your mana rocks every turn
Lately, we've seen indestructible being lent to your team via Avacyn, Angel of Hope or Rootborn Defenses