The BB syncs seamlessly with the Outlook calendar and contact list on my computer in the office, so it is worth it to carry one for that alone. I am planning on purchasing an iPhone for personal use in the next month.
While I have used Roadmaster base plates due to the fact I bought a Roadmaster tow bar used, I too have found using Ebay to find the best prices works well. I usually pay around $300 and often shipping is free.
If you can find a used tow dolly, you can probably sell it for what you paid for it when you reach your destination.
Have you looked into what it will cost to rent a car in Florida and turn it in in Oregon? That could be quite expensive.