Idea of electrical cost

Hi,

I know I may not get the exact answer I am needing but I just want to get a sense of how much it would cost to wire a outdoor studio that is 15m2. I feel like my the amount I have been given is a little astranomical. The room is connected to the house and has a junction box and power point, lights and an aircon that was put in. Despite the aircon which I was quoted wholesalers price and my nephew connected this roughly what would I be looking at price wise. Also how long would the ex[expectation to finish this.
Nicole

Thankyou