Actually, I was wrong. There are a good amount of .303 British and other small bore doubles online, though most are at a pretty high price. This is what I was able to find currently available for sale online:
Webley & Scott .280 Nitro -- $11950
Joseph Lang .300 H&H -- $42500
I. Hollis & Sons .303 British -- $29500
Holland & Holland Royal .303 British -- $39750
Beesley .303 British -- $12950
Holland & Holland Royal .303 British -- $35000
Alexander Henry .303 British -- $17900
Jeffrey .303 British -- $7500
I do think the .280 Flanged and .30R Blaser are cool rounds but it is really hard to beat the .303 British for old school British cool.
I am also looking at Anderson Wheeler as they currently make .303 British doubles, although I doubt they will do it for the price of the AyA.
In my mind, the benefit of buying new is getting a gun with proper stock fit, modern materials, and desired barrel length. While I have heard that there is no velocity gain for the .303 above say 25", I do think that a 28" version would be really cool.