Trademark protection in the Benelux starts at EUR 244 and in Europe at EUR 850 for a ten-year period. Note that depending on the number of classes of products/services that you choose, extra costs may apply.
Protecting your trademark internationally will probably be more expensive. You can estimate the fees you may have to pay using this link.
Mind you, official trademark offices such as BOIP for the Benelux or EUIPO for the EU do not send invoices. Upon filing your trademark application, you will receive confirmation by e-mail. The confirmation is also intended for your administrative records and contains an overview of the payable fees. Scams exist however, so be careful with invoices you may receive, even if they feature a logo. Check everything you may receive regarding your trademark application, registration or renewal very carefully.
Contact your trademark office to authenticate documents in case of a doubt.