Well, it seems to me that PLUMs are in China and Leopolds in Japan are the good deals right now. So assuming you've read the reviews and know what you're getting those are the good deals. AFAIK Duckys aren't as cheap.
Ducky's are quite cheap, especially with cheap shipping from PCHome.
PCHome Ducky shipping (up to 5 kg, a keyboard is 1-2 kg) US: 10$, EU: 20$.
Leopold shipping (FC500R, the fullsize one) US: ? EU: 5400JPY - 67.33$ - 46.60EU
Leopold shipping (FC200RT, the tenkeyless one) US ? EU 4800JPY - 59.41$ - 41.42EU
Ducky 1087 price PCHome: 1990TWD - 69.10$ - 47.83EU
Ducky 9008G2 price PCHome (abs): 3190TWD - 110.79$ - 76.68EU
Leopold FC500R price: 8980JPY - 111.97$ - 77.50EU
Leopold FC200RT price: 7980JPY - 99.50$ - 68.87EU
Total cost to EU (keyboard + shipping):
Ducky 1087: 89.10$
Ducky 9008G2: 130.79$
Leopold FC500R: 179,30$
Leopold FC200RT: 158,91$
The Ducky 9008G2 & Leopold are in the same price range, but due to the expensive shipping from japan and the cheap shipping from taiwan ducky's are (atleast for me in Europe) a lot cheaper then leopolds.