I have read Duguid, and he is indispensable. I would also recommend Karen Jobes (in the NIVAC series) and Joyce Baldwin (in the Tyndale OT series, which has now been replaced by Reid's commentary, so you'll have to find Baldwin second-hand).
Didn't mean to scare you. It's not a big book at all. Mine is hardcover and I suspect that's all there is, but it won't be priced much higher than the typical paperback. I just found it listing for $12 US on Amazon. I imagine you could find something comparable. P&R is the publisher.