I have assigned a value related to a value slightly below the rumored "refusal" level for DVC. I would currently use about $55 per point and feel I can easily defend that level of value.
On other timeshares we own, I base it well below our purchase price, since traditionally timeshares retain little of their original price level. I will usually base that value less than (normally far less than) 50% of what I paid.
While I'm certain I could value these properties much higher, this method is well within my comfort level as I'm confident I can easily defend the values assigned in this manner.
Some other considerations for me are the age of the resort, whether the developer is still selling properties and the strength of the capital reserve of the resort (an indication of the intent of the management to sustain a level of physical repair).
Often times when applying for a loan - you must prepare a personal financial statement - detailing your assets, liabilities, annual income, annual expenses, cash in banks, etc....
DVC was a big investment for us - and, I feel, holds a great value - and I just felt it was too "valuable" to be left off of my statement.