I currently have a 1 year, Multiple Entry (L) Visa valid until until the 14th of June.

But i want to stay until around July 14th. Is the best way to do this (Money wise) to go through the PSB? What are the alternatives besides going to an agent in Hong Kong?

I've been living in China for almost five years, having graduated from an international school in Guangzhou in May 2013. I'm currently living without notifying the local police of my location, but my mother still lives in Zhuhai. I had no problem at all when applying for a visa through an agent in Hong Kong, but it cost me around 4500 Hong Kong Dollars for a year. Is it likely that I'll experience difficulties if I go through the proper channels? What will I be looking at price wise? Thanks for any help you can give me.