Cheapest priced copy (Foundations Commander): $0.35 at Card Kingdom, near mint, their price list as of .
Tamiyo's Logbook 
Artifact — Book · Uncommon · Phyrexia: All Will Be One · #70
{5}{U}, {T}: Draw a card. This ability costs {1} less to activate for each other artifact you control.
Legal inCommanderPioneerModernLegacyVintage
Not legal inBrawlStandardPauper
2 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations Commander | 76 | Uncommon | $0.35 | — |
| Phyrexia: All Will Be One | 70 | Uncommon | $0.35 | $0.49 |
One ruling from Wizards of the Coast
- 4 February 2023The cost reduction of the activated ability applies only to the generic mana component of the activation cost. It can't reduce colored mana costs. Even if you have five or more artifacts, it still costs {U} to activate.