Pricetag of 3D Model of shisha tea bar (signs of getting lazy/american brain spill)

Hey folks,
On saturday my boss called, saying I have to change and that he will pick me up in about twenty minutes.
He owns an old two story building, where used to be a gym, pub and pawn shop.

So, fast forward a bit - I was sitting in his car (brand new Mercedes-Benz S600 V12, of course, ugly car, but I love the engine) and the boss man told me that he will need me to make a 3D model of the palce.
We got to the place with box full of keys to separete the ones which are compatible to it's locks and doors from the rest, which we figure out what they are for another day.
And that was my saturdays job.

This guy pay people per task. he tells you what he needs done, you tell the price, you do it, you get paid on that day.
Now, I am a little uncertain about how much should I ask, because so far I did 3D modeling just as hobby, past time, time killer. Never for money. God forbid custom model for somebody. And my question is what number (meaning price) should I spit out when asked about it.

I did 101 seconds long google search and I found that pre-made models are being sold for hundreds of dollars. But these are pre-made, based on real world objects like stadiums, bus stops, hotels, restaurants, gas stations,... put on sale for wide public.
And I wonder, if the price is calculated by square meters? Number and quality of details? Time spent making it? Or is just pulled out of thin air?
But this is gonna be custom made model for just one person.
The place's size I should make my vision of is approximately 50x30x5 meters.
The place is awfull-falling-apart-concrete-monstrosity at the moment.
I have some raw idea of what could it look like (bar, some bean bags, tiny tables, armchairs, terrace in front,.. main texture would be wood.. dimmed lights), but before I start doining anything I would like to know if it's gonna be worth the time I spend making it.

Just spit out some number with dollar sign near it and your thoughts and opinions. I'll read them, maybe post further questions&answers later.

It's my first time fullfilling this kind of order and I don't feel quite confident about price tags I should go with.
Hope you won't come up with some two figure pricetag example that would be time&energy waste to even say "fuck off" to this guy considering I'm to create it from scratch.

Oh, and about the „signs of getting lazy/american“ part in the title.. that’s because I usually don’t ask questions about probably already answered questions.. Today, I’m just lazy to do a fucking reasearch, which is gonna be longer the couple of minutes. So I thought I might write and post a post about it and see what turns up. Now I’m just gonna need to filter out the fellow-non-lazy-jealous-entrepreneurs „do your own fucking research!!“ bullshit comments and check what sheeple’s gonna say.
Isn’t that called outsourcing?