I've mongered in china. Been to shanghai four times. And Anon123 is correct. Your biggest barrier is the language and secondly that you are a foreigner. If you can get around the language thing, I assure you its worth it. I had the locals that befriended me to set me up. She told me how much to pay, and definitly to tip wisely, if at all. Of my six experiences, four were outstanding, one was a starfish and one couldn't get over the fact that I was "not caucasian".
The Motel168 chain is not only affordable, (at $30/day for a single and I think $40 for a double) but comfortable. Free highspeed internet, tv with english channels, ac/heat unit, good maid service, but rock hard beds, and no amenities like saunas.
I did the bbs scene, mostly hj/cbj, had one fuck and it was lousy. Cost 200 to 300 yuan. (and yes I went to the ones with the pink lights. White lights are the legit shops.) Did the foot massage places, mostly hit and miss, some do and some don't; the one good hit stayed with me for free after I fucked her in the shop. Showed her the little jacket you keep your hotel key in, she pointed to the clock and held up 10 fingers and at 10:30 she knocked on my door.
Tried the bathhouse/sauna routine and it was a wash. Pun intended. They just couldn't get pass the fact I wasn't caucasian, that's not an indictment, just the facts.
Outcalls are the best. 400 yuan for 3 hours. That's like $16 bucks an hour, my kind of deal. No freak or kink sex though, just the straight stuff, but they can hang.
Don't ask me for names of places or streets or directions, hell it took me one week to learn to pronounce "ni hao" correctly. But if you are patient and don't expect a PI or LOS experience, you can have a good time.
That's my post, and I'm sticking to it.