Go to any of the hot tocs at NPK and the girls will have sex with you. You have to pay extra, but you can bargain with them.
If you want girls to come to you, get on WeChat or Line and there are unlimited amounts of girls on there willing to have sex with you. This is why I like HCM more than other cities in Vietnam, because options are limited on these apps elsewhere, whereas HCM has as many Vietnamese girls as you can imagine on these apps all working freelance.
There are also many hot tocs that run along the small water canal separating District 3 and Phu Nhuan District. These places are known for full service, and Vietnamese locals pay less than foreigners. Here are a few hot tocs on the water canal:
Kim Yen Hot Toc / 1073 Hoang Sa, Ward 11 District 3, Ho Chi Minh
Thanh Cong Hot Toc / 991 Hoang Sa, Ward 11, District 3, Ho Chi Minh
Huynh Phuc Khang Hot Toc / 1096 Truong Sa, Ward 12, District 3, Ho Chi Minh
And all over Saigon, you will find barber shops that focus on full service:
Hai Yen Hot Toc / 815 Le Hong Phong, Ward 12, District 10, Ho Chi Minh
You can expect to pay around 1,000,000 VND ($43 USD) to 1,300,000 VND ($56 USD) for full service at most hot tocs, and you can always negotiate.
There are also Vietnamese hugging cafes all over Ho Chi Minh. Some places are just coffee shops with sexy Vietnamese girls working as staff, but that is not what I am talking about. The Vietnamese call these places "caphe om" which translates to "hug cafe" and they are adult lounges. Before blowjob bars got popular, these places would often have girls who gave blowjobs to customers in private rooms in the back. This doesn't happen as much anymore, but the Vietnamese girls still dress sexy, encourage customers to buy drinks while flirting and rubbing their bodies on the customers. Here are a couple "caphe om" Vietnamese hugging cafes you can check out:
Tro Lai Caphe Om / 698 Pham The Hien, Ward 4, District 8, Ho Chi Minh
Cafe 714 Caphe Om / 714 Pham The Hien, Ward 4, District 8, Ho Chi Minh
If you find a girl you like, you can walk out with her to a nearby hotel and full service will cost around 800,000 to 1,000,000 VND.
Little Japan in Saigon / Thai Van Lung, District 1, Ho Chi Minh Little Japan in Ho Chi Minh is a small, walkable area of District 1 that is everything Japanese - hotels, spa services, food, etc. And all over this area, you will see some of the most beautiful Vietnamese girls, all wearing tight fitting Vietnamese traditional clothes, and are very pushy and aggressive about trying to sell their massage and spa services. The general problem with these places is the incredibly high prices that they demand, which are often times paid by Japanese, Korean, Chinese, and Taiwanese travelers visiting Saigon. At the end of a typical work day, you will see many traveling businessmen in Little Japan Town, and they love these massage girls and spa places. Once you agree to a massage, the girls will offer additional services. Every massage place in Little Japan slightly differs, but here is a general idea on what you can expect to pay for sex at massage places in the Thai Van Lung area:
700,000 VND ($30 USD) for the massage room
1,000,000 VND ($43 USD) extra for handjob
2,000,000 VND ($86 USD) extra for blowjob
3,000,000 VND ($128 USD) extra for full service
The Vietnamese girls at Thai Van Lung are extremely beautiful, but paying 3,700,000 VND ($158 USD) for sex is very expensive. The Japanese and Korean businessmen love this area and have no problem paying these high prices, so from what I understand, there is not much room for negotiation because the girls are very firm on the cost for extra services after you pay the initial massage ticket.
Line / WeChat
If you want to avoid the blowjob bars, massages, and spa places in Ho Chi Minh, you can always have a local Vietnamese girl come to your room. The easiest way is to download Line or WeChat, both apps are free to download for iPhone or Android. You can use the People Nearby feature to find local girls who will happily come to your room. I recommend you completely negotiate the transaction before agreeing to have them come over. Every girl will quote you high prices to start, and you can definitely negotiate. Some girls are local students freelancing for extra money, and others are locals who manage multiple girls and send them over to meet you. You can expect to pay around 1,000,000 VND ($43 USD) for full service, which is one hour or one cum shot. And if you spend a bit more, the girl will stay overnight with you. Here you can see a running thread showing pictures of Vietnamese massage girls and the prices for sex.
It's also very easy to meet local Vietnamese girls on Kynu.net for sex in Ho Chi Minh. You will have to use Google Translate to communicate, and you will be required to meet the girl at the love hotel of their choice, but you can browse photos of the girls and find out how much each girl is asking for sex. Read the reviews for the girls, be sure to factor in the amount of time and energy required to make an appointment for meeting, and add in the cost of the hotel (expect to pay for 2 hours at the love hotel). This site primarily caters to local Vietnamese men, but you can use Google Translate and meet many girls for sex in many districts all over Ho Chi Minh.
You can find sex in many places around Vietnam, but Ho Chi Minh has the largest population and the most options for finding girls for full service. I recommend you read over the discussions and reviews that others have posted on the forum here. And please let us know what works for you to help others looking for the same thing. I love hearing reviews about other people's experiences.