Wanting it in three parts gives you lots of options: remove the duster for a back seat, run just the Bikini, lose the Windjammer for a hot day. It's a nice way to go. Just price out those three parts. They're on our website under "Accessories," and popular at all the big internet retailers, etc.
And BigTyme: absolutely. One, two or all three. (although a duster and bikini combo might be a bit weird).