Here are a few options which may help...

Premier Inn Haymarket (www.premierinn.com/pti/home.do)
Rooms from £70 per night

No. 3 Bed and Breakfast (www.no3edinburgh.co.uk)
Rooms from £65 per night

Bed & Breakfasts within 10 mins walk of the venue:
Martin’s (www.martinsguesthouse.co.uk)
Granville Guest House 0131 229 1676
Kaimes Guest House (www.kaimeshouse.co.uk)
Prices start from £20 twin share/£30 single

Backpackers in the city centre, all within a 10 min bus journey
Budget Backpackers (www.budgetbackpackers.com)
Caladonian Backpackers (www.caledonianbackpackers.net)
Hoppo Backpackers (www.hoppo.com/edinburgh)
Prices start from £10 a night