Japan also designs & builds world class D/Es,but they would taking a huge diplomatic risk hawking those to Taiwan.Other designers include Sweden & Holland,who have hedged their bets on China long ago.
PS-The German fuel cell based AIP appears to be the best around,but Sweden,France & Russia are all offering different AIP systems for their subs,with an average (continous) underwater submerged endurance of 10 days or more.
As far as I know the Netherlands produced the two current Hai Lung class boats used by Taiwan since the mid-80ties. There are 2 more boats of the US-guppy class (anno domini 1945) but they do not count anymore. All this equipment is hopelessly outdated. Taiwan needs around 8 subs to answer the red Chinese threat.
In May 2002 Taiwan's legislature passed a resolution requiring that at least six of the proposed eight subs must be built in Taiwan with US help. In late June 2002 the cost of the eight submarines was reported as being as much as US$6 billion, making them the most expensive weapons system Taiwan has ever bought from the United States.
The Taiwanese dismissed a American proposal to buy submarines being buildt in Israel. They wanted German technology and nothing else and counted on US-pressure on the German government. This attempt did not work. In May 2004, Jane's Defence Weekly indicated that Northrop Grumman Ship Systems is offering Taiwan a modernized version of the old US Barbel - class submarine. NGSS would like to partner with Howaldtswerke- Deutsche Werft (HDW). The design of the submarine would use the Barbel's hullform fitted with an HDW pressure hull and modern components such as AIP. The submarine would have a submerged displacement of about 2,644 tons, a maximum speed of 21 knots, a range without refuelling of about 19,000nm and six torpedo or missile launch tubes. The likelihood of the deal is extremly uncertain as elements in Northrop Grumman appears to be cool to the idea, and it is unclear if the German government would approve HDW's transfer.
Personally I do not believe that Schröder is moving one inch in this case. Hehe! The US probably have to break a taboo and will sell Los Angeles cass nuke subs to Taiwan. This subject will remain exciting in the future.