Edinburgh, near the Uni -
Salisbury Green - Actually on campus £69 a night
URLNice B&B - £55 ( might be cheaper - phone and negotiate )
URLRecommended hotel on the South Side- 10 Hill Place. Quote says £140 a night but you should get it for around £100.
URLWhats your budget ?
If it is around £60 or less I would steer clear of the hotels and go for a Bed and Breakfast.
Accommodation in E'burgh is expensive.
Threre are plenty of good Guest Houses in the Mayfield and Cameron Toll area. There are good bus routes so I wouldnt worry about transport.