Newegg offers the Cooler Master 120mm Silent Case Fan 4-Pack, model no. R4-S2S-124K-GP, for $15.99. Redeem this $5 mail-in rebate to cut the price to $10.99. With free shipping, that's the lowest total price we could find by $4, although we saw it for $3 less in summer. It runs at 1,200 rpm and features air flow of nearly 45 cfm with a 19.1dB noise level. Rebate expires February 26.