No the risk is limited and anyway if you get some counterfeit money you can always use it. I cannot make a different between fake and not and I am sure I got some but never had any problem from someone telling me that I carried counterfeit dollars, actually the rate yesterday was 16,780 so the most reputable place is close to the hang da market I do not have th street name with me but it is a small street in angle where they sells as well motorbikes seats you will find the shop there.