Cheap knockoff stuff in China isn't that bad.

A good quality rain suit is going to cost you ¥300 but you can buy a decent knock off for ¥80... knock off every time.
A helmet is never worth risking, find a reputable brand and source as mentioned by others here.
Riding Apparel: Unless you're going to invest in Aerostitch, BMW, Klime, etc. most of the mid-grade China stuff is actually pretty good. You can buy two complete sets of gear from Nerve ( 1 mesh for summer and 1 regular for spring fall) for the cost of 1 pair of BMW gloves.

If there's any chance you have the opportunity to hit the motorcycle market in Guangzhou, you can get some excellent stuff for very little money. Plus you can try it all on and be sure of what you're getting. A lot of shops there get samples from production runs for name brands and I've walked out of there with gear that would have cost a fortune if I bought it back in the states.

Cheers