The local markets in Ho Chi Minh city are huge.  They sell everything you can possibly imagine.  The buildings are cram packed with vendors selling their wares.  I personally enjoyed shopping and buying Vietnamese silk in some of these markets.
Certain areas of the markets include local seafood.  And the smell of the food area is quite overwhelming.  Especially for those with a weak stomach!
The people are very friendly although you should expect to be approached or lured by almost all of the vendors.  
The sheer volume of products found in these markets is amazing and so many items are hand made or hand crafted by the locals, as this, for many, is their livelihood.  
The prices are very inexpensive by comparison of the US Dollar.  I purchased several 100% Vietnamese silk robes for $20 US.
A definite place to check out - as a Westerner - it's an experience you'll remember.