Hey neil, don't take this the wrong way buddy but "welcome to the club". Loads of people in your situation, for example mikec who started the following thread...
http://www.multimadrid.com/cgi-bin/jersbbucgi/ultimatebb.cgi?ubb=get_topic&f=11&t=0000 12... is willing to spend up to 75.000 pesetas/month for a room in Madrid and he can't seem to find anything
The problem with segundamano is that most of the apartments there are "controlled" by "agencies" that sucker you in and try to get you to pay them a fee to help you find a place with no guarantees. A few weeks ago I was helping a non-Spanish speaking friend call around and we phoned about 30 places that seemed normal but about 15 of them were the same agency with 10 different phone lines
I wish I could be of more help in that area with my website and in order to start off on the right path, I have launched a monthly classifieds section at
www.multimadrid.com/classifieds that is complete with apt. rentals/shares and loads of other services. This is in conjunction with the InMadrid newspaper here and I hope to update the section monthly before the 1st of each month. The best part is that although the InMadrid newspaper is limited on space for their classified ads, online there is no limit so we should be able to put many more ads up.
One downside to this, the people who place ads have to have them in by the 15th of the previous month and what usually happens is that 50% or more of the rooms/apts. for rent are rented to friends of theirs via word of mouth before the ad even goes up.
It is a very tricky situation but we are doing our best
Saludos,
jer...