The question you've asked here is equivalent to asking someone to build you a house, and expecting to get a price, based on that description!
The cost of the product depends on the specification. If you want an app that says "Hello world", that won't take me very long, and will cost you very little.
You've said nothing about the features required. Those numbers you quoted in the above article are rough guides. How many hours you actually need to spend developing this depends on a lot of things. For example
- What's your skill level?
- What's the specification?
- How much time will you have available to spend on it? Is it part time, or full time?
- What's your relationship with the customer?
- Is it just you working on it, or will you have help?
- Does it involve graphical elements, such as icons. Are you able to create these?