I went to Vietnam from 9 - 16 June. I spent 8 days there of which 1 full day was spent at the airport.Inclusive of my taxi to Changi Airport there, my expenditure for the trip was close to SGD 1,150 assuming a USD/SGD exchange rate of 1.3. Bulk of the expenditure went to the flights, as I had to make additional trips to visit the other cities of Vietnam - Ho Chi Min, Danang and Saigon. My friend chose to stay in a budget hotel and that was a bit steep for me considering I was alone in the room and he could share it with his girlfriend. Nonetheless, I found the room rates acceptable considering that I do not intend to stay in a bed and breakfast style inn, yet.
SGD 1,150 seems like alot of money at first glance for a place like Vietnam. However, that is a a slightly reasonable amount considering that we flew quite a bit, so no regrets there. Also, while I felt Danang was a wee bit quiet, it gave me a break away from the more commercialized cities such as Ho Chi Min and Hanoi.
Overall, I would recommend people to go to Vietnam thru the cities I have listed. If you can stay in each city slightly longer, it would be better as there were some day tours that I did not manage to sign up due to time constraints. It was a 7.5/10 holiday.