There’s a few things you need to consider here. Firstly, the Dutch political parties don’t start campaigning until just before the elections. In comparison, last year’s campaigns for the US presidential election started in 2015.
Second, Wilders does not like to say to much about his campaign finances (and there are people saying he might be actively hiding some donations). For most large parties in the Netherlands the numbers vary from 500.000 euro to about 2 million euro. But for the PVV the true number is unknown. Small donations don’t need to be public and political parties often have it’s members pay into the campaign funds as well. Most likely, the PVV is spending somewhere between that 500K and 2 million number.
Thirdly, the Netherlands is much smaller than the US. Less people to campaign to also means less money is needed.
Lastly, the US elections are really expensive… Seriously, really expensive.
