I'd go for Rebas, get an older model heavily discounted and you'll grab a £500 set of forks within that budget. Plush as you like, easy spares, good resale price, infinitely adjustable.
what he said
PARTS FOR SALE:
vintage Brooks Professional saddle | Specialized FACT CX fork | Columbus fork | Reynolds 531 fork | Avid Arch Rival v-brakes | various 700c, 27" and 26" wheels | vintage Weco hubs (fixed/freewheel) | vintage Raleigh ladies frames + lots more!