LOL... I had the opposite problem. I'd planned on cosleeping, and my son would have none of it! Nonsleeping baby until I set him in his crib as a safe place while I did *something* (forget what) and he conked out. First real, honest to god sleep he'd had. For hours. Experimented a bit over the week, and by the end of it... he was in his crib in his room. That kid just needed his own space! He started piling into bed with me about 50% of the time when he was 3, and at age 9 it's still about 50/50.
((I'm serious, though. He wouldn't sleep in bed, in a cosleeper, or in a bassinet. He needed to be able to sleep with his arms and legs straight out and not be touching anything. Goofy kid.))
So I'd say to save your money for now. If it turns out later you need one (if you end up with a kid like mine!) get one then.
As far as the nursery goes... get a playpen! I half LIVED in my rocking chair in there (lazyboy)... again ebf mom, not by choice, but my breasts don't pump (:P) and my husband has a thing about being woken up. So the rocking chair is probably unnecessary for you.
A fairly empty room, however, is a GREAT place to speed crawl, learn to walk, play toss in, keep a changing table.