I will be in Edinburgh for a weekend in December. Does anyone know where I could buy tartan curtain material (in the city)?

Depends whether you want trad curtains or something you wrap round poles. Depends how heavy you want the curtains to be ...
One possibility is simply to buy some lengths of lightweight kilt cloth. Loads of venues on the Royal Mile. Also available I would think from big stores e.g. Jenners.
Kilt cloth could be pretty saggy unless the curtains were appropriately constructed.
For curtain material try big department stores like Lewis's at the E end of Princes street.
Places like Jenners or Lewis's will point you in the right direction even if they can't help.
Remnant Kings Edinburgh (The Cloth Shop)
169 Bonnington Road
Edinburgh
EH6 5BQ
GB
Telephone: 0131 554 7733
Take your check book with you ;-)
Edited: 7:49 pm, November 20, 2012Thanks a mil for replies. I will check all places suggested. Would you know if The Cloth Shop on the Bonnington Rd is within walking distance of the city centre?
Google maps is a handy device. it does post codes :-)
And the answer is it's a mile or so north of the centre, what it doesn;t tell you so easily is you can get a 11 bus down Leith Walk and Pilrig St or a 36 bus from George Street.
A pity RK have messed up their website otherwise they could have told you that themselves.
Try http://www.martonmills.com online as they will give you a better material and price than the Royal Mile shops.
I have just returned from Edinburgh this evening after a super weekend and am pleased to report that I am now the proud owner of several metres of tartan curtain material! Ended up getting it from The Cloth Shop on the Bonnington Road and am really delighted with the quality and especially the colour. Thanks again for your help.......I would never have found it without you!