There are much cheaper models available in the UK. Inlander make a fridge freezer to work on 12v or 24v systems such as this one on ebay (I have one of these) ...
http://www.ebay.co.uk/itm/Inlander-12v-24v-Silver-Fridge-Freezer-Boat-Caravan-Mo...

Shoreline do a whole range of 12 / 24 volt frides, freezers, and fridge freezers. All compressor type so suitable for solar systems. Much cheaper than the units available in Spain .....
http://www.shoreline-marine.co.uk/

Waeco (Dometic group) also make 12v fridges/coolers which might be suitable ......
http://www.waeco.com/en/58.php

These could also be suitable alternatives. Whilst the Sundanzers work off solar, They are expensive and based in the USa so shipping will be very expensive.

John.

Thanks for the info. Our secondhand gas fridge is still working fine but when it eventually bites the dust we will need to consider the options. As our battery/solar system is rather limited at the moment we would probably have to stick with gas- cheap in the winter but gets expensive in the summer.