use a signal instead of calling QMetaObject::invokeMethod
Create an enum for price sources

Probably settingscache would have been the correct place for the enum,
but keeping it in the same class/file where price sources are defined
sounds cleaner to me
Added default cases to switch
Ensure all card prices are retrieved correctly

Query card database to get a multiverseis for a card.
Get card price using that id instead of card name.
Tested Aether, split cards, question elemental?, _____