Hello blancpain,
Sounds like a good plan to me. Add swiss balls, kettlebells and Pilates or Yoga and offer your customers low tech, high Performance fitness solutions.
Einstein once said: "Everything should be made as simple as possible, but not simpler". I think that´s exactly how physical exercise should be: simple but not primitive.
Use good, inexpensive equipment and the best available knowledge and you are able to offer a premium product at a very reasonable price.
Go ahead and let us know, how everything turns out.
Best wishes,
Olaf