It also depends on how long the property you are trying to buy has been on the market and what shape it is in. I've had cash buyers miss out on properties many times because they are in better shape and bring competing buyers. Sellers will take a financed buyer who will pay more than a cash buyer who offers less.
You need to analyze everything that's sold in the neighborhood within the last 90 days and take into consideration the length of time the home has been on the market and what shape it is in.
Contact an agent who pays for and has access to the full MLS records as they can see how long a property was listed and how it sold and if there were any seller concessions.
I live and work in Vacaville and keep track of the stats. Sorry to get to this question so late in the game, but in the past three months (June-Sept 3) foreclosed homes have sold for 98% of their list price. The MLS doesn't allow me to separate out cash sales, but my experience is that cash sales tend to sell for aprox 90-95% of list price.
Hope this helps!