Buy Vietnamese Dong in Cambodia?

Hi, my friend has just bought some Dong in the UK but at a poor rate, can I buy Dong in Cambodia for a reasonable rate? I'd like to have a little before I cross the boarder.

Thanks

Very easily done; I usually buy around $50 worth at the money changers outside Central Market until I can reach HCMcity where the rates are obviously better. However, the rates around the market are only slightly less that in big cities in Vietnam and certainly better than exchanging at the border.