Need help wording a special stipulation

[George Ramsay]

I have a lender that will loan me up to 70% of the ARV of a property. That 70% is only applicable to the Purchase price and rehab costs. My concern is that if i estimate the ARV over what the bank says it's worth I need to be able to walk away w/o losing my earnest money. So me and my agent have been trying to find a way to word this into the special stipulations, but were struggling to do so.
Something like
"Buyers Lender must appraise property for X amount of dollars"
Any ideas would help.