For all you .450/400 shooters, there is an auction on ebay for a box of 50 Woodleigh RN SN 400 grain, .408 diameter bullets on ebay:

.450/400 Sn Woodleigh Bullets on Ebay

Also, there is an auction from the same seller for FMJ bullets:

.450/400 Woodleigh FMJ

The seller is in Australia, but ships worldwide. I have no connection to the seller or items listed - I'm just posting this incase someone is looking for them. Current price is less that $8 US.