Grund Stump Grinding

After calling around for ballpark prices for grinding, I was considering renting a small grinder for a day to do it myself.  I was told ballpark pricing would be $5 / inch.  So a 20" diameter tree would cost around $100.  Most of the quotes were between $550 and $650 since I had 7 trees at one small location.
Then I saw a sign in front of a house near me advertising Stump Grinding.  I called and left a message.  They called back and came out for an onsite estimate.  It was a high-school kid - very professional, who did this when he had time.  It is a family business and his Dad has been going it for many years.  Now the son is the main contact.  After getting quotes for $550 (lowest so far), I was taken aback when he quoted me $165.  He said he's cheaper than other services because be thinks it's fun AND he has a HUGE grinder that allows him to get the job done FAST.  I told him to do it and he came over two days later.
He has a small pickup that he tows the grinder behind.  It's a large hydraulic unit and it chewed through the wood so fast, he was done with ALL 7 stumps in less than one hour.  He even offered to chew up some parge diameter surface roots that were near the larger stumps.  He needs access to the stump with his truck so if you have limited access where his truck can't fit - he's not the guy for you.
He was super polite - really mature for a Senior in High School.  I paid him in cash and tipped him $20.