Theasian why did your agent tell you that the offer needs to be in the 520-530k range? Let me ask you a few things…
How long has the home been on the market? How is it priced compared to comps? Did your agent call the other agent to get information? If the home is really priced very aggressively then it would not surprise me if that is the case. If the home has been on the market for a few months at the price you are talking about then perhaps you are right.
Unfortunately looking at the last sale is meaningless. The lender doesn’t care about that. The lender will price the home at what the lender thinks they can get for the home. The process includes thier own analysis as well as the lender ordering a BPO, brokers property opinion. So take those things into consideration.