The price of a taxi application like uber (or any application for the matter) largely depends on the following factors:

What are the features you want included in the app? An app that is loaded with a lot of features, it will cost more than a more minimal model.
How extensive you want the application to be - Do you want the best of graphics, sound-design and user interface? That will run up your budget more than a more simple app built on a basic design.
Time of development - The most important factor when it comes to determining the price of the app. The more man-hours that go into developing the app, the more the pricey the app is going to be.
The type of app you want - a clone application like Uber Clone will be a much more cost effective solution for the budding entrepreneur. Those who can afford to spend a bit more can go for one that is completely built from scratch.
Customization - How much customization goes into the app. Making the app fit the mold that the customer wants is a time consuming process that can rack up the expenses.
Additional services - There are a lot of services offered by developers to elevate your business to the next level. Things like marketing, post-launch maintenance, customer support etc. These all can be availed for an additional cost apart from the cost of development.

The price of an app can vary depending on an individual’s specific needs, so it is hard to give an estimate without knowing your business requirements. For an accurate estimate, consider getting in touch with a reputed Uber clone developer.