Hi Emmy,
When it comes to keyword research everything is time consuming. If you want a refined list of keywords you need to dig into it, however I find it always reliable since I structure every idea around the terms I find.
What I normally use for keyword enrichment is:
- search for my terms in google and see what kind of suggestions google gives. These are not synonyms but terms highly related, then I click into them and find new related ones
- group my main terms and put them into google keyword tool. In that way google will give you suggestions of related terms, jsut try to expand the list as much as you can and then refine it.
- again in google keyword tool external you may look at your competitors' homepage or to the competing urls in your serps and see which keywords they have. If you find that many of them are using supplies you amy consider adding that term too, since it will be giving you more new keywords to rank for.
About what terms go for, google always tries to give to the user the best result. In that sense Google analyses the related terms, evaluate them and then it mixes them up to try achieve the best results, there are terms which are high related synonims like motorbike and motorcycle and other which are less like motorcycle and bicycle. Depending on how much you're content is, you may consider extending your content to add new related keywords, or may be you want to create totally new sections pointing to those new keywords and deliver your users there.
hope this helps!
