Calculate ARV if there are only new houses for comparison?

[Ava G.]

I was asking in another post that I'm planning to do my first house purchase for a flip. But let's say in doing ARV, there're only brand new houses as a point of comparison for the market value of the property I am looking at. I don't live in the US so we don't have the websites / tools ya'll use to do market research (e.g. to know whether a property was sold brand new or rehabbed). All we have are local listings of the selling price of brand new properties (mostly).

For example, I am looking at this property:

Selling Price: $22,193

Floor size: 100 sqm

Lot size: 70 sqm

No. of Bedrooms: 2

Toilet&Bath: 1

Car Garage: 1

Now, in the same area (about 3km radius), 2-bedroom SFHs are selling for (F - floor size, L - lot size in sqm):

F: 90, L: 100 - $42,537

F: 94, L: 91 - $55,537

F: 72, L: 120 - $33,290

F: 80, L: 80 - $51,000

F: 84, L: 63 - $48,000

However, these are brand new. Is there a better way to roughly calculate the ARV based from these numbers? Like, should I lower the ARV by e.g. 10% as compared to a new house? Let's say, on average, a new home of the same type is selling for $45,000 multiply it by 10%, means I should deduct $4,500 to get to my final ARV.

Any thoughts?