Excuse me, are you in Guangwai South Campus (University Town) or North Campus (Baiyun Mountain)?
If you are in the north campus, you can cross the street at the main entrance, take bus No.424, get off at Baiyun Park subway station, take subway line 2 to Guangzhou South Station, take 1 BC line (to Xilang), get off at Huadiwan Station and take the CD exit. The market is at the exit.
If you are in the south school, the subway needs to transfer more. Also, take the bus from University Town to Metro University South or University Town North (forget which station near Guangwai), take Metro Line 4 to Huangche, turn to Wanshengwei to Line 8, then turn to Changgang to Line 2 to Jiahe Wanggang, and turn to 1 at BC. Everything else is the same. I have to transfer to the subway three times. This is less than taking Line 4 to Chebeinan, changing to Line 5 to Guangzhou Railway Station, changing to Line 2 to BC, and changing to 1 (also three times).