Collins appealed the sentence, saying the fine outweighed the charge, but failed to appear when the matter was first called.
He later failed to file submissions, and failed to appear again when the appeal was heard in court. The High Court dismissed the appeal on September 6.
"Mr Collins has clearly chosen to flout the law," the High Court judgement said.
"Previous fines have obviously had no effect on Mr Collins. He knows the fines have become progressively more severe, but he continue to offend nonetheless.
"Judge Paul observed, when he sentenced Mr Collins in June 2014, that fines imposed in this area cannot be regarded as a licence fee to break the law. It is clear that Mr Collins now regards fines in that way because he appears content to pay them in order to continue reoffending."
The court believed Collins was "not willing to deviate from his chosen path of offending".
Motor Vehicle Traders registrar Stephen O'Brien said Collins "knowingly broke the law on numerous occasions by continuing to sell cars while banned from registering on the Motor Vehicle Traders register".
"Between 2001 and 2014 Mr Collins received five convictions and fines for selling motor vehicles when not registered as a trader and for trading while banned.
"This latest fine reflects Mr Collins' repeated and intentional flouting of the law for commercial gain; a compelling factor for the judge to impose the maximum penalty for individuals of $50,000.
"The Motor Vehicle Sales Act is there to protect consumers by ensuring traders abide by certain conditions, such as not being banned from motor vehicle trading or being bankrupt, and requires traders to provide purchasers with information and also allows recourse through the Motor Vehicle Disputes Tribunal.
"Consumers can check their trader is registered on the Motor Vehicle Traders Register to ensure they have protection should there be issues with the vehicle," O'Brien said.
