We bought a Peugeot partner that has been pretty reliable from a company in Amposta. Can't remember the name just now but I will post again as soon as it returns to me. They are easy to find. They have a lot just off the Amposta N340 roundabout...the one with what I call "Neolithic construction crane" sculpture you can't miss them. We got a five year old vehicle with a years warranty,itv and a towbar fitted with necessary paperwork for about 6000. Pricey compared to UK prices but vehicles seem to hold their value longer here.

I got a ten year old Nissan micro previously, with bodywork a bit knocked about,over a hundred thou on the clock but a great runner that was considered a bargain by friends for 800euros. Would have been about £200 or less in the UK. Still using it just over four years later though so I am not complaining!
I also know of friends who have had good results from one of the van dealers on the 340 in Vinaros.
They also offered a years warranty that was honored with no quibbles. I will find the name of that company too if you are interested.
Bruixot