The first option ( you build) is the 4th house.
The second option buy an existing property would be the 4th from the 4th, that is the 7th house.
Option one is ruled by moon near the 2nd house cusp, exactly squaring sun.
Sun rules the 6th, so there may be difficulties finding workers to build the house.
However, overcome this phase, moon will sextile Venus, you, and Jupiter, 8th house ruler. So you should be able to get either a mortgage or funding for the work.
Both Venus and Jupiter are in the 12th house, showing some type of impediment, or that you aren't fully aware of the situation.
Option two is ruled by mars, also in the 2nd of your money, as moon of the first option.
However, mars only makes a square to Neptune in the 12th.
This is a red flag, something you don't know about, that isn't what it seems, or confusion about the issue.
Also, possible over-spending of your finances. Mars is an active planet that can consume, and quickly!
While it looks like mars will trine Saturn, in reality Saturn will change signs before mars is in aspect.
Ascendent ruler Venus is in the sign and Face of mars, but there is no mutual reception.
You haven't included the South Node in the chart, but it falls in the 7th house. This is a second negative note to consider, you will have to give way somehow on this choice.
You also haven't inserted Part of Fortune, which falls at 2 Leo. Exactly square the 7th cusp.
Quite a few considerations going against Option 2.
It's difficult to find a chart that is "perfect" and shows clear and easy solutions, so you have to just be aware of the possibilities and make a choice.