Went to tai cheong, the uncle is quite friendly.
Saw many drivers all over the shop, guess mostly not for hi-fi speaker...
Went over martin electronics too, saw the lady drilling holes for amp chassis...
Tried talk to her, they don't seem to sell used driver. But they do have new driver
On the way back, popped into well audio lab and had a quick chat with the uncle, a nice guy with good knowledge on speaker driver, though they don't sell speaker driver
hope to see more guys sharing their lobang place for used or old drivers :)