As a victim of the American school system who hardly remembers any of the grammar that I was briefly and leniently taught, what would be a good grammar to buy?
Are you searching for good grammar books? :D
For basic level, I can recommend you some as below.
1) Basic Grammar in Use With answers,with Audio CD : Self-study Reference and Practice for Students of English (Grammar in Use)
2) Basic English Grammar
I, personally, prefer the former. It's clear and easily understood only the audio is OK. Hope that helps. :D