A professor friend would like some background on retail pricing of early LPs.  He cites Frank Sinatra's "The Voice" on Columbia 10" for instance.  

It looks like Decca based pricing on the number of cuts or sides.  

Four 10" 78s=3.75
Corresponding 10" LP of same 8 sides/selections=2.85

Five 10" 78s=4.50
Corresponding 10" LP of same 10 sides/selections=3.85

Did the Columbia product fall somewhere in the same range and can any print sources be cited?  

Thanks!  :-)