Hi... I live in the UK and we regularily go over to Munich and Salzburg, after having our honeymoon there 28 years ago and apart from the large shop posted in a previous message in Munich I have yet to find a large quilting shop. I did buy some beautiful traditional fabrics in Salzburg a few years ago now but even then it was very expensive.
We think that fabric in the UK is really expensive but it is even more so in Germany and Austria and you might be really taken back by the cost......I hope you have a wonderful time though...Salzburg and Munich are simply stunning....When in Munich if you go to the Englischer gardens on a sunday you will see lots of people in tradition costume, alsoif you get a chance to go to Hallein (home of where Silent Night was composed)...that is lovely and taking a cable car up Untersburg mountain is simply stunning with views over Salzberg...as are the lakes at Mondsee.......there is so much to see you will have a wonderful time...take a great camera and enjoy.......