Another tip , lux - in towns/cities ask about the "Hutongs" (I think the literal translation is : 'old lane') in the area (not so much the touristy ones) .
Ones to look for would be , for instance ... Luomasi - the "mule & horse market" , Gxngwasi- pottery market , Zhubasi-jewelry market (all in the city of Beijing) ... the point here is to see such areas , maybe make contacts there & see what sorts of items/products are up for sale .
Since you're going to Nanjing & Shanghai , there's not too much left , as far as really old & diverse ones (Hutong) .
The drive to build new commercial structures in those two cites has eaten up most of the old Hutong real estate .
When I've visited the rural areas , I always do so with a good friend (who is a Chinese national) and discretely inquire about old mementos that might be for sale , rather than wait for someone to approach .
Doing so , even in remote areas may put you 'on the radar' with officials , so I am always 'straight-up' & honest with folks there .
When possible , I like to hang out for a day or two & meet folks & their families ... this also allows more time to sniff around for cool items .
I have invited 'officials' to a meal together in such small towns & sometimes they'll accept (not a great idea for the faint-of-heart or the translator-less , though) .
Rural folks easily recognize foreigners , IMO .
In the 'country areas' , I prefer to just buy only one or two small items & am not bashful about doing humorous & friendly bantering/bartering/bargaining (through translator) .
Like gingertomantiques mentioned , be kinda careful when/where you pull out your camera , and be respectful of folks & locations , since 'lawbreakers' can be dealt with rather stiffly .
If you're going to be covering all that territory , you'll have to figure out how to get larger items where(&when) you want them ...either that or drag them along with you .
I usually go for small items & bring them along the trail .
