Be carefull with Dutch travelinsurance. They usually only apply for people actually residing in Holland. ( Because basically the travelinsurance won't have to cover medical costs, as your standard Dutch insurance would cover that ) But in the case of a Dutch expat, a standard Dutch travelinsurance is worthless !
I bought also several times with http://www.hccmis.com
as mentioned by Gerard. They are very cheap and you can buy it online.