Buying a Headstone

My dear Brother passed last August and the funeral and casket and plot came out to $25k, the family hasn't been able to afford a headstone yet, so we are starting a savings and trying to purchase one soon. Can anyone tell me where you go yours from for a Houston (i-45 North) cemetary and how much it cost? Also, does the headstone company place it for you or what happens after you order it?