If you are looking for an inexpensive/budget place to stay in Dar es Salaam, then you might want to consider the Saadani Tourist Center.
I discovered this establishment by accident one day while looking for accommodation for interns from work. I was immediately impressed with the organization and pleasantness of the place.
The exterior, complete with a small swimming pool, was brightly decorated and felt particularly inviting. The staff was very accommodating when I tried to find out more about the establishment.
Something to watch out for is the location. Saadani Tourist Center is located in the residential area of Mikocheni not close to a main road.
Finding transportation could be a little tricky, but then again there are several ride-hailing services in Dar es Salaam now, such as Uber and Bolt, so there are ways around this.
Saadani Tourist Center is very well priced.