Hi, I'd like to know where can I take the bus from Suzhou to Zhangjiagang?

The South Bus Station, North Bus Station and Main Railway Station North Square Bus Station all have direct coachs to arrive at Zhangjiagang. In general, the duration is 1.5 to 2 hours.
Hereunder is the detailed bus schedule:
South Bus Station: 06:20 - 19:20 at intervals of around 20 mins. CNY 28-49 per person
North Bus Station: 06:00 - 21:40 at intervals of 20-30 mins. CNY 28 per person
Main Railway Station North Square Bus Station: 06:55 - 22:00 at intervals of 30-60 mins. CNY 28 per person
Hope helpful!