I have one moleskine; I use it for my poetry. It cost around ten pounds which is the most I've ever paid for a notebook, so I wanted to make sure I'd use it for something I'd want to keep, not just notes or shopping lists.
I have a BlacknRed for what remains of the second draft of my WIP. That cost around £2:50.
And I also have a small, suedette-bound notebook for my daily thoughts; I call it an 'epistolary journal' because it's addressed to someone but they'll never read it. That was £5.
Other than that, I write on scrap paper or in cheap notebooks. But yes, moleskines are so lovely that I want to buy another one. I just can't think of what to use it for. My next novel's first draft, maybe? Or because there would be corrections and crossings-out, would it be an unnecessary expense? Do others use moleskines for rough drafts?