I have purchased fabric from all of the places you mention. When they say 'thin', I think they mean thread count. Some fabric is thin, but beautiful and great quality.
On the other hand, some fabric has a lower thrread count and just feels less silky, even rough. Since you are doing Baltimore Album, you will need small pieces of many fabrics. Fat quarters from an expensive shop might not be too bad and do not forget your friends. I have given may pieces (large scraps) to a friend who was doing an applique quilt and delighted to find someone who wanted them.
Someone just gave me a blouse that is hopelessly out of date color and style-wise, but beautiful material. It has found a home.