Flights from India through Air Asia has been dirt cheap. I booked an Air Asia flight from Hyderabad to Ho Chi Minh to & fro for roughly 15,000 INR only (Approx 200 USD). Thus, if you are aware of the offers, the chances of cracking a deal is very high. Usually, the best way to find cheap flights is searching from a country rather than from a city. In this way, the search engine will show the cheapest flight from a different destination. A great way to find cheap flights. I usually use Skyscanner or google flights to search for flights & for booking the flights, I either choose a carrier website or some online portal which are offering cash backs or discounts.
Accommodation is pretty cheap in Ho Chi Minh. I stayed at The Hideout Hostel, which is one of the best hostels to stay. The location is superb & amenities provided by the hostel is good too miss. There are plenty of other options to choose from. One can use platforms like Agoda or Booking.com to make a booking. A typical hostel dorm bed starts from approx. Rs 400 (USD 5). However, the rates are dependant on the season. Thus, the rates may elevate depending on the time one wishes to travel. I would recommend booking at the earliest.
Ho Chi Minh is a great place for 2 or 3 days. There are plenty of things to do some of these are Cu Chi Tunnels, War Ramnant etc. All the paid activities are worth visiting. The prices start from 15,000 VND (Vietnamese Dong) (Approx 50 INR or 1.5 USD). If you are short on time, you can shortlist few activities & only do them. However, Cu Chi Tunnels is a must visit activity.
Food & Beverages:
Food is a special attraction in Vietnam. There are dedicated cooking courses for tourists. Eating on the streets is super cheap & super delicious. A plate of noodles or rice will cost you around 20,000 to 25,000 VND (Rs 60 or 2 USD). Further, the price of beer starts from 12,000 VND for a can. The prices are standard across the supermarkets & the number of these supermarkets are ample.
If you are spending wisely & appropriately. The budget of INR 1000- 1500 (20 USD to 25 USD ) is enough for the day. This budget is assuming one is staying at hostels & without shopping for luxury items.