According to a source at Let the Voters Decide -- the 3rd-party petitioning group Kanye's been using this summer -- the rapper's campaign paid them between $3.5 and $4.5 MILLION across 15 states to send workers out for John Hancocks.

We've covered many of the individual states where the group has been dispersed on Kanye's behalf, but we're told one of the biggest chunks of money went toward Arizona -- where Ye allegedly dished out $1 million to get 93,000 signatures -- only to have a judge bar him from the ballot anyway.

The same is true in Ohio and Virginia -- where our source says Kanye's campaign allegedly spent $325k and $300k respectively to gather signatures ... only to not make the ballot.

As we reported, Kanye also spent at least $30k with LTVD in Illinois -- and that ended poorly for him -- and though it's unclear what he spent in Wisconsin ... he's currently been booted from the ballot in that state too for missing a deadline by just seconds.

Of course, without paying big bucks to Let the Voters Decide, he likely wouldn't have made the prez ballot in states like Kentucky -- where we're told he spent $400k -- or Iowa, where he dropped $80k. He's currently made the ballot in 12 states.

BTW -- the bill keeps growing for Ye, because as you recall, he's already reported $6 million he's spent and disclosed in his first financial report with the FEC earlier this month, which outlined various disbursements to other companies to get him on various ballots.

So, it begs the question ... is it all worth it? Kanye's running as an independent, but many believe his campaign is being fueled by pro-Trump operatives and having his name on the ballot will mostly hurt Joe Biden. Ye denies he's working with Trump and co.