Should we buy our house? ?

Our landlords wants to sell us the house we're renting. When we first started discussing it they said they thought it appraised for 93,000 and were going to sell it to us for 85,000. The appraiser came out and said it appraises at 83,000 so our landlord said they'd sell it to us for 83,000. Since they were willing to sell it for so much less than what they thought it would appraise at to begin with should we try to get them to sell it to us for less than the appraisal now or should be just buy it at 83,000? Plus I don't know that we'll want to live here for ever so do you think we'd be able to sell it later for what we owe on it? Does the vaule of the home go down over time if the house is kept in the same condition and no improvents are made?