You said the bank would only consider it as valued at the sell price? I thought ( I am new to this please don't get to mad) the bank when they do the loan value the house. If that is correct and say the value of the home is 100,000 and the seller is just wanting out of it and willing to sell for less would I be able to get the money based off that?
The mortgage lender would consider that market factors are creating the true value of that home. I may think I have a painting worth $10k but if all I can sell it for is $7k then that's what it's worth. The value of any item at any SPECIFIC moment in time is what it can be sold for at that very moment.
A real estate appraisal is based mainly on recent home sales in the area adjusted for differences between those homes and the one being appraised. It isn't a guaranty of value but a risk-mitigation method of the lender. Just in case you are buying something for over a fair market value, the lender wants to make sure.
A home loan is a loan collateralized by real estate. You won't find a lender willing to do a loan greater than the value of the collateral. Especially not in the current market environment.
Now if you did purchase a property at a discounted sales price you could look to take advantage of equity in the home typically after living there for 6 months.
I hope this helps.