Only interesting thing I ever found in Tianjin was the big market area by the metro/train station towards the new dev area. I made my way to the back one day and found a ton of Craftsman tools being sold for pennies on the dollar. Scooped up as many wrenches and tools as I could (busted or not).
I felt like a thieve buying 3/4" and 1" ratchets for $5. 1" deep impact sockets were like $0.50.
This was a few yrs ago, so this may not be the case anymore.