I paid £90 p/w for my halls which weren't anything special but it was decent enough to live in. A good sized room with a sink, plus a fairly modern kitchen. I wouldn't really want to pay much more than that, i couldn't give a **** about these expensive ''super deluxe premium en suite'' rooms that so many universities are insisting on building these days.
I think the 'per week' figure makes it seem more expensive that it actually is though. I worked out that i'm paying £85 per week for my house once everything is added together (rent, bills & council tax which i'm paying by myself), over 12 months that comes to £4420. Whereas a £120 p/w 40 week contract in halls would come to £4800. Virtually no difference.