For banks it will probably be an unsecured loan. Some of the resellers can help make financing arrangements. Your options
1) Pay cash (my favorite). No interest, no payments.
2) Home equity loan or line of credit (probably the lowest interest rate - mine is well below Disney's. )
3) Buy from DVC and use DVC financing (interest rates aren't bad, but I don't think they are great either)
4) Reseller helps find financing (some people have reported getting rates that closely match Disney's)
5) Arrange for a loan through your local bank. Some will balk with the word "timeshare" involved. Interest rates will vary.
6) Arrange for a personal loan. (i.e. Mom and Dad, its the opportunity of a lifetime, and with your help...)
7) Credit card financing. Some people have good rates on credit cards - in some cases, excellent rates for six months, and if you can pay it off in six months (or play the credit card transfer game), this can save you a lot in interest.
A home equity loan or a DVC loan MAY allow you to take a tax deduction on the interest. Obviously, not everyone has cash, a home to take a home equity loan on, or parents willing to float them $10k.
There may be some more ways to finance. You may want to talk to your bank before you begin looking at resale contracts - or talk to the resellers.