well, generally speaking computer hardware in taiwan is 10 to 20 percent cheaper than the uk, below is a link to a typical taiwanese computer website, in chinese ofcourse but i navigate it and i barely speak a word of chinese.....
http://www.arclink.com.tw/
thatll give u an idea, although i too paid over the odds for my 7800 gt, i paid 16200 NT dollars, which is about 290 british quids, bout 80 quid more than in uk!
but on the other hand i paid 11050 for my x2 3800, which is 197 quid, or 18 quid cheaper than in the uk, so almost 10 percent cheaper, but it ranges, things are cheaper, but not many people have money here, they earn about 1.50-2.00 US dollars an hour for working at KFC!, the average income for a person sales manager for example is 35000NT a month, or 1000 dollars a month, and thats fairly good for taiwan, being a foreign teacher here however i earn double that 😛, ahh english, i love it!