Many of the resale brokers have finance companies that they work with and I have heard that the length of the term is dependent on how big your purchase is.
Through Disney, the loan is considered a mortgage and typically the interest can be claimed on your taxes (but you have to check for your own situation) and it is not reported on your credit report (so it doesn't show up--for some, this is a good thing).
I think that the interest rates are similar. Disney is currently 10.75% (preferred with direct debit) for up to a 10 year loan and the company the Timeshare store uses is advertising at 10.99%.
Good luck!!