I just posted this in another thread. 80mm - 120mm forks. Not much at or below the $400 mark. My favorite fork, at the moment, is the Rockshox Reba Dual Air but they don't make those anymore. Probably a Rockshox SID Worldcup would be my next choice or RTC3 if you want 120mm.
Pricepoint has a Marzocchi Corsa SL at a decent price of $379.
Or a Manitou Tower Pro 80mm QR15 $399. (I think this is the one SN bought).
Or a Marzocchi 320LR 100mm QR15 for $468.
Manitou Tower Pro 29er Fork QR15 140mm $399
Manitou Tower Pro 29er Fork QR15? 120mm $399 <<---- Might be your best deal if it is QR15
Jenson USA
Marzocchi 320 LR 29" QR15 Fork 2014 for $422.10
Fox 32 Float 100 CTD Evo 29" Fork 2015 $545 (best price on a Fox Fork)
Universal Cycles
Fox 32 Float 100 Terralogic FIT Forks Tapered QR15 2012 $499 (decent price on new old stock)
Fox 32 Float 100 O/C CTD 29" Forks Tapered QR15 2015 $545
ProBike Supply
2015 Fox 32 FLOAT 100 CTD O/C 29" 15QR 1.5 Tapered Steerer Evolution Fork $545 (This is the fork I have but I have the remote lockout)
2015 Fox 32 FLOAT 120 CTD O/C 29" 15QR 1.5 Tapered Steerer Evolution Fork $545 (If you want 120mm of travel)
Wiggle (free shipping from the UK)
RockShox Reba RL 29er Solo Air Tapered Suspension Fork $514.27
RockShox Reba RL 29er Solo Air Tapered With PushLoc Remote Fork $515 (100mm is out of stock but they have the 120mm)
X-Fusion Slide RL2 120mm Tapered QR15 29er Fork $449
B.W Baker Bikes
Magura TS6 29er 120mm QR15 Suspension Fork $449 (Not positive if it is a tapered steer tube)
http://bikes.bwbaker.net/Item_i318570