Cheapest priced copy (Urza's Legacy): $0.35 at Card Kingdom, near mint, their price list as of .
Silk Net 
Instant · Common · Urza's Legacy · #112
Target creature gets +1/+1 and gains reach until end of turn. (It can block creatures with flying.)
Legal inCommanderLegacyVintagePauper
Not legal inBrawlStandardPioneerModern
1 printing · $0.35 to $1.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Urza's Legacy | 112 | Common | $0.35 | $1.49Out of stock |
2 rulings from Wizards of the Coast
- 4 October 2004Both the +1/+1 and reach only last until end of turn.
- 1 April 2008This card now uses the Reach keyword ability to enable the blocking of flying creatures. This works because a creature with flying can only be blocked by creatures with flying or reach.