I don't have any personal experience with them, but NoiseBlocker BlackSilent-PRO 140mm fans come in 900, 1400, and 600-1500 (PWM) versions, with static pressures of .73, 1.24, and 1.42mmH2O max., respectively, which is close to the NF-A14 when running at similar speeds. May be an option if you can't find the NF-A14 for a reasonable price, or you don't care for the colors of noctua fans.
Just going by specs, the SP140s aren't that great, at 1.17mmH2O and a much higher 29.3dbA (compaired to the nf-a14's 24.6dbA and the NB BS-PRO's 23.7dbA). I'm sure they aren't bad fans, but I'm not confident they'd be quiet and performant after my experience with the SP120s that came with my H80i.