Like most Magic: The Gathering cards, the value of Phyrexian Scriptures depends on a few consistent factors: its rarity, the printing and finish (regular or foil), its physical condition, and the set it was printed in (The List)
Assuming proxies will solve a social problem
More recent video game promo cards have been Super Rares
Here are all of the cards you need for 'Triumphant Light Museum 1': Houndoom #76 (Full Art / One Gold Star) Marill #77 (Full Art / One Gold Star) Unown #78 (Full Art / One Gold Star) Sudowoodo #79 (Full Art / One Gold Star) Magnemite #80 (Full Art / One Gold Star) Shaymin #81 (Full Art / One Gold Star) Rewards: 36 Wonder Hourglasses, 12 Pack Hourglasses and 10 Shop Tickets
While it surely has its origins in 60-card Constructed formats, I believe the adage rings true in Commander as well
[[Idol of Oblivion]] also doesnt cost you resources, as you arent sacrificing Artifacts for the draw