A lot of money?
Trumps campaign has been bankrolled between 35% and 55% of Hillary's (Depending on whos figures you believe).
Trump has run a genius campaign based on internet white noise, and the fact that no publicity is bad publicity...
Early on he actively funded internet bloggers and staff to promote the hilarity of his running in the primaries, his strategy was literaly 'how ridiculous is this lol' which gained a huge amount of free online publicity. After this he drowned out every big announcement by the other primary candidates with hilariously bad videos, do you remember the girls dancing on stage cringe video? Released the same day 2 other candidates were making big anouncements about their campaign.
His campaign has been an anti establishment message, and if like me you have followed US politics for years, you'll recognise his 'outrageous' comments have been mere reiterations of hundreds of politicians before him.
He's designed a characature of crude, ignorant and unashamedly common guy who wants to rattle washingtons cage, mainly because a huge amount of Americans can identify with that.
I would go as far to say that, if ANY democratic representitive over the last 30 years ran against this type of campaign Trump would be crushed come day 1, however his campaign is beautifully set up against the most corrupt representitive in history.
PS admiring the campaign strategy doesn't mean I agree or support him, you don't have to be antisemetic to respect Hitlers taking of mainland europe so easily and quickly.