With a good agent and/or a favorable situation, you may be able to get nearly to zero in costs. But those are the rarer cases (nearly everything is negotiable, as I am sure it has been made clear).
A good rule of thumb is 2%-- give or take a 1% margin. These costs tend to account for escrow and title costs.
These costs can also be split with the buyer and the seller or even taken wholly by the seller (good agent and a good seller)
As a cash offer, you dodge the biggest cost and time taker in the modern home buying experience, that being the loan costs.
However depending on exactly the home, costs and abilities for the seller to cover them can vary.
if you want an individual analysis, talk to anyone of us.
You know nearly each and every one of the southern California realtors here are willing and able to help you one-on-one, if you have not already chosen your representative.
Give any one of us a call. We LOVE helping.