There may be a Criss Cross Directory : Hendersons/Wigley etc - These can be searched by Name this shows address -and sometimes occupation.
Can be searched by Address - this will show names of all persons at the location.
Searching City Directories/ Telephone books for Music Stores [there are probably not to many to search] may show names.
Perhaps there are Volunteers at Random Acts of Genealogical Kindness - Alberta - http://www.raogk.org/alberta.htm
who may be able to help.
Claresholm City Hall/Municipal Hall - may hold business licenses etc - perhaps they may assist.
Happy New Year 2009 - Cheers, Stella