Tom, you have several good options. Hobie always ships with the Drive, but some dealers will credit you for the Drive, paddle etc., and sell them separately. Call around if your local dealer isn't interested.
Another option is to buy the complete boat and sell the Drive yourself. I sold two of my older Drives very easily last year locally on Craig's list. They hold their value nicely! One person wanted a spare and the other lost his Drive in the ocean and needed a replacement.
A final thought -- The Hobie kayaks are worth a lot more with a Drive than without when it comes time to sell later and get a newer boat. It's not a bad investment just to hang on the Drive until you sell the boat.
BTW, with your assortment of Drives, the newest ones will be the best, most durable and improved -- you could always "trade up" and let one of your older ones go.
