The Trump campaign reported receiving $100mm in gifts in September compared to about $154mm for the Clinton campaign. $2 million of the $100 came from Trump himself. In the last debate, Trump also estimated that he would contribute about $100 mm in total to his campaign which presumably included the primaries as well as the general election.
One of the features of the Trump campaign that has been much discussed was the presumption that it would be self-funding. Some voters did not like this idea, saw it as trying to buy the election. Others liked it a lot. Put in positive terms, it meant that the candidate would not be beholden to all the special interests (aka crony capitalists) who give to politicians but expect something (policy, favors) in return.
$2mm in September is not very much these days, nor is $100mm overall. And the idea that Trump could and would finance himself has no doubt reduced the amount of other gifts. The question now arises: did Trump decide not to invest more or was he unable to? Perhaps no one will ever know for sure.