Cheapest priced copy (Commander Masters): $7.99 at Card Kingdom, near mint, their price list as of .
Synapse Sliver 
Creature — Sliver · 3/3 · Rare · Commander Masters · #857
Whenever a Sliver deals combat damage to a player, its controller may draw a card.
Legal inCommanderLegacyVintage
Not legal inBrawlStandardPioneerModernPauper
3 printings · $7.99 to $37.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Commander Masters | 857 | Rare | $7.99 | — |
| Legions | 53 | Rare | $9.99 | $37.99 |
| Secret Lair Drop | 626 | Rare | — | $21.99 |
2 rulings from Wizards of the Coast
- 1 July 2013Abilities that Slivers grant, as well as power/toughness boosts, are cumulative. However, for some abilities, like flying, having more than one instance of the ability doesn’t provide any additional benefit.
- 1 July 2013If the creature type of a Sliver changes so it’s no longer a Sliver, it will no longer be affected by its own ability. Its ability will continue to affect other Sliver creatures.