The phrase 'Bob the Billder' refers to a stingy, tight, or overly expensive builder or manual contractor. It can also be used in reference to general laborers who are forceful or pushy when collecting their payment at the end of the job.
The phrase likely originates from popular children's TV show character, Bob the Builder, combined with the financial word 'bill'.
PERSON 1 : “That'll be $50m for the sink replacement, fella.”
PERSON 2 : “WHAT??? Fine, I'll send the cash. But you're a serious Bob the Billder, you know.”