Generally I find the goldshops to be more reasonable than the hotels but do not flash a lot of money around at them.
Also the Western banks seem to have a higher limit on money that can be taken out , HSBC , ANZ and Comm Bank in Sai Gon.
And Banks are OK , however, some shut at Lunch time.
Oh , and dont expect that all retailers accept Credit Cards.
Keep your money in your front pockets and keep all valuables away from the street side . Bag snatchers on bikes are common in Sai Gon.