I just bought 4 eQ-3 HomeMatic wireless thermostates for 25,- euros a piece which is pretty cheap as the are selling normally for 38,-euros.
http://www.eq-3.com/products/homematic/heating-and-climate-control/homematic-wireless-radiator-thermostat.html http://www.elv.de/homematic-heizkoerperthermostat-1.htmlThey come with adaptors for the most german radiators and as ELV/eQ3 are the most known european homeautomation based seller i guess that they would fit on netherland ones too ?? To get them working wireless you would have to buy a CCU which is the gateway/automation/software point as the are 868 type, which costs 80 euros more, but you can build yourself a nanocul (arduino nano with CC1101 module) for arround 5 euros and install Homegear or YAHM (which ist the image of the CCU software) on a raspberry pi.
Right now i am trying the 4 homatic thermos with homegear running on a pi, and homegear turns every in and out going 868 signal/value into MQTT, which is going in the installed mosquitto broker so i can use Node Red for automation and building blocks or MQTT Dash (android app which is quite nice) for controlling and setting the parameters.
I am now searching for a way to get the mqtt values into HomeGenie to use the perfect timer and automation features of HG, so it would be the perfect setup