Recently, there are so many people asked me, "can you build an apps for me?" First of all, I wish to ask what is the purpose to your own app. Well, the most popular answer is "I wish the mobile users can access the information in my website!". So, I will recommend them to build a responsive website.
To build a responsive website is only adding a mobile css and maybe jquery tricks into your existing website. That is much lower cost. Moreover, the user is more prefer to enter url rather than installing an app.
Nowadays, mobile apps sounds a cool stuff which everyone wish to have, but we need to ask whether you really need that. There are plenty of choices out there!