Private financing question

[Farris Roach III]

Need some advice BP! I am looking into a possible 12 door property in my area. My question is regarding financing. I plan on going with a private lender for funds but not sure how much I will need. This is a property that I part of an auction. The price is reasonable but I'm sure the auction will drive up the price. My question is how do I know how much to ask for from the private lender? I dont want to bid 200k, win the bid and not have the money to back it up! Please tell me what route I can take.