I went to the Jaoji Lu moto mart and got them to reupholster the seat with way more foam than was necessary. I saw a local Shanghai police bike with an overstuffed seat and asked for something similar. The seat mod I highly recommend, you can even bring them some memory foam if you want to get fancy. I paid 30 RMB and the guy spent 45 minutes putting it all together for me. You should also be able to get panniers and a rear box on Jaoji Lu for a cheaper price than what you'll get on Pubei Lu. I'm not a fan of tank bags but I know others who love them.

The shocks are another story, and I wouldn't recommend you start swapping them out on a new bike. I should do a write up on my Frankenstein's monster bike. The only original parts are the frame and the front wheel.

Shop around and keep us posted on what you buy. I find myself living vicariously through the other members here as I try to get up the gumption to buy a new bike myself.