Cheapest priced copy (Time Spiral Remastered): $0.39 at Card Kingdom, near mint, their price list as of .
Sidewinder Sliver 
Creature — Sliver · 1/1 · Common · Time Spiral · #41
All Sliver creatures have flanking. (Whenever a creature without flanking blocks a Sliver, the blocking creature gets -1/-1 until end of turn.)
Legal inCommanderModernLegacyVintagePauper
Not legal inBrawlStandardPioneer
3 printings · $0.39 to $7.99 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Secret Lair Drop | 615 | Rare | — | $0.99 |
| Time Spiral | 41 | Common | $0.59 | $7.99 |
| Time Spiral Remastered | 43 | Common | $0.39 | $0.99 |
3 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.
- 19 March 2021Once a Sliver has become blocked by a creature without flanking, the blocking creature gets -1/-1 even if the blocked Sliver loses flanking before the ability resolves.