Good grief...the comments on Hacker News never cease to amaze...
...just to give a representative example, last September my Dad died. 1) We had his remains cremated. 2) We got said remains without anything fancier than the cardboard box they came in. 3) We scattered his ashes ourselves as a family without any visitation, funeral ceremony, or anything.
No gravestone, no casket, no wake, no ceremony, no officiant.
Total cost: $6,000.
$20,000 is absolutely realistic if he wants to be buried with an average casket, average headstone and average ceremony.