Getting keyword idea is never easy.  You may need to test thousands of keyword variations before looking into the search volume of each keyphrase.  Ubersuggest is a very good tool for generating ideas and variations by adding different characters and numbers to your searches, so as to return suggestions from Google Suggest feature.    This handy tool allows you to export all the returned results (which I believe commonly a list of hundrds of combinations) and you could simply dump them into the Google Keyword tool to get the search volume.