Places to stay

It would make sense to stay somewhere near-ish the Playfair Library (Old College, South Bridge, EH8 9LY) and/or South Hall (18 Holyrood Park Road, EH16 5AY), though staying centrally in general is probably best as you are going to want to go other places.

If you would like the convenience of having your hotel room a mere crawl from the the reception venue, have a look at Edinburgh First accomodation run by the University. A 15 - 25% discount applies to these rooms, so it's worth having a look.  

Air bnb is an affordable and comfortable way to go.  Amy (sister of the bride and maid of honour) and Sarah have had excellent experiences with CouchSurfing but Air bnb might be a better option for most guests. Amy recently used it while traveling in Boston and New York and thinks it's great. Check the Edinburgh page to see what's available.

Youth Hostels: Castle Rock Hostel in the Old Town usually gets quite good reviews and the Caledonian Backpackers is quite popular, as well. Obviously, there are loads of these places and we live here, so don't have much first hand knowledge to go on, but if you can reccommend anywhere in particular, please post a comment and give folk a hand with their selections.  

Camping:  Free or wild camping is legal in Scotland as long as you're responsible about it.  Did a wee search on camping areas in Scotland and THESE SITES came up for Edinburgh.

If you're very skint, you could always crash on the floor of chez Stewart-Hutchison, but, for obvious reasons, we can't have you all :(