Are you asking about manipulatives..or just books. If it is just books, all you would really need are the workbooks, textbooks and the HIG's. Normally I wouldn't say you need a teacher's guide (because the concepts are so easy), but if you don't learn to teach your children the way that Singapore teaches, when they get a little bit older, the method will get confusing to them...if they learn it young, it will be so much better. So, get the HIG's and use them.
As far as manipulatives, many things you can make, find or create at home...but if you go to the Singapore website, there is a page that lists the manipulatives by book that would be helpful in owning. IF you are unable to find it, let me know...I can probably dig it up again.
Kathy