Hello: I am a small business owner with an assortment of 150 items in my store.

I do have a mobile domain and yes, it is a mini version of my site !!!! The domain was registered to protect my brand name.

I have finally decided I do need an App for my site. Do I need different Apps for Android, IPhone, etc. ???

I have read prices ranging from $2,000 to $10,000. I don't want to get an App for my online store simply for the sake of getting an App if it won't work for my customers.

Protecting my customer information is # 1 priority.

Pardon my ignorance for asking these stupid questions but I have no idea where to start !!!!

Hope

Do I need different Apps for Android, IPhone, etc.

Yes, native apps are specific for the operating system, the same way that the same piece of software won't run on a Windows PC and a Mac.

I don't want to get an App for my online store simply for the sake of getting an App if it won't work for my customers.

Without knowing the details, this may or may not be the case. In most cases, a very mobile-friendly site is sufficient. You only need a native app if it needs to do something that you can't do through a web-based environment. For example, Facebook has a mobile friendly website, but they also have a native iPhone app that has additional functionality such as importing your iPhone's photos, etc. that aren't as seamlessly done or even feasable at all through a web-based interface.

If you have an online store, think about the types of people who would be buying from you and the frequency in which they'd be buying. Is being able to buy on-the-go by browsing to your website and purchasing through your mobile-friendly interface sufficient?? In most cases, the answer would be yes. How many people are going to take the time to search/find your application in the Apple App Store, download your application, install your application, and have its icon permanently on their phone's start page, just so that they can buy 1 or 2 of 150 items once.

On the other hand, if you sell digital eBooks, for example, you might want to have a native application that can give someone quick access to purchase and install it right into their eBook reader while on-the-go.

I have read prices ranging from $2,000 to $10,000.

As with anything, it depends on the complexity :) Apps can go into the six figures, even. It really depends on the complexity.