Newbie need help for project

So I am planning to participate in some challenge. I should make something like this:
Project to locate item, the thing I make with Arduino should be connected to phone via Bluetooth and attached to item I want to locate, and when it gets out of range, phone starts to vibrate or to produce some sound until user click something on mobile. It should also produce sound if I want to find it, I click on mobile app or something.
Can I get any suggestion on what should I buy and how to do it?

That is one question.
The other is if I want to show last location of item, how could I make that? (This question isn't really important, but I would do it if I could finish my project on time, I'm focused on first one).

If anyone wants to help further please contact me.

Judging by your forum name and subject, you're totally new to Arduino? I really doubt if this is a project for a new-comer.

Have you worked through any examples like those at File > Examples in the IDE (also available here) to get a feel for Arduino? Do you have any electronics and / or programming experience?

I would say I had little experience with Arduino but it is really little. I have programming experience, actually I am IT student.

Well, two things.

One: Most of the programming will be on the phone.

Two: Arduino not involved. Bluetooth modules have intelligence and will respond on their own.

Three: Why duplicate an already readily available and mature system?