Where to exchange money in Busan other than banks?

Hey Koreabridge community out there, I would like to know where can we exchnage money in Busan other than banks.??  

It doesn't matter whether its black, grey, legal, illegal as I am a student and I need to exchange a certain small amount of money every month for my survival which my family sends me. 

I have heard that there are some AJUMMAS in Nampodong area, if anyone knows about that kindly tell me the exact location or any such other place in Busan from where I can get the rates which I can see on internet or atleast close to it.

And if there is no such place exist, what is the best way to exchange to get the best rates or which bank is better to have good rates??? 

I am expecting some quick answers from our koreabridge community who I believe know about Busan better than anyone else^^ Thanks a ton for your will be answers :))

Re: Where to exchange money in Busan other than banks?

ONLY GO TO BANKS!!! If you are trading a "small amount" for example $500 and the rate is 1145 as it was a week ago versus 1185 as it was yesterday that is a difference of 40 won. That is a difference of 20,000 won. Not enough to deal with sketchy people, and I dont think they give you that much better of a rate... Any bank can change your money with a passport or your ID card. Methinks something else is going on here...