The size of the room (i.e. your floor plan or room size) is important as well to estimate sizing. Some of y'all may be living in Damansara heights where the living room is my whole mini apartment
Some combos of AC placement and room shape may require bigger hp aircon.

Used split AC not economical unless really cannot afford a new AC because any repair will be out-of-pocket (point #1) and when you pay for this repair it will most likely cost more than even buying the cheapest GREE or Midea 1hp AC (brand new NON inverter unit with warranty)..so its a bit of false economy (point #2).. and depending on previous owner maintenance may have smoke smell or other funny smells. Lapsapda and Chopee have installment plans for things >500 or >1k pricetag so can split to 12 months EPP

AHX9VED on shopee ~1200 or so if self collect (find own installer after MCO) https://shopee.com.my/Sharp-1HP-1.5HP-2HP-J...6163.1394376296

As for 2hp/2.5hp technically also depends on sizing of the room and how hot it is normally.
We had a good run with a window casette (old type) 1.5hp (suspect to be quite high btu) that was immensely cold for the living room