@protoaddct I thought of something very similar, only with no legendary rule (could be used as a path to restrict Workshop and Bazaar without really busting up the deck. That way the entry for those decks would also be substantially more affordable). They could release "Vintage Horizons" and make something like:
Tap to add 2 colorless. Use this mana only to cast or activate artifact spells and abilities.
Yardsale of Yemen
Tap to add 1 colorless OR tap to draw a card and discard two cards
@forceofnature I thought something very similar; Urza's Workshop has not been used as a card name so I was going with that and, in addition to giving you two colorless usable only for casting artifacts, having the mana from Urza's Workshop be able to be used for activating artifact abilities as well.