What I have done with great success is to go to the local tartan shop (I am lucky in that there are several in the Toronto area) and see about ex-rental jackets or jackets on consignment. Another technique that has worked for me is to troll ebay, I would suggest going to:

www.ebay.co.uk

They have more selection than the American site, it may take time to find exactly what you are looking for however it is in my mind worth it.