This all depends on where you are in the escrow period and if you have removed contingencies.
– If you have not removed contingencies yet then you can retrieve pretty much all of your deposit back. If this is a condo you will need to return the HOA/CCR/Bylaws back or pay for them if you want to keep them
– If you have removed contingencies then it gets a little sticky. You can request that the seller returns your escrow deposit less sellers costs. It will be up to the seller. If the seller does not want to return the money you can go to small claims to get the money back. If you signed a mediation and arbitration clause in the purchase agreement you will need to go through those paths at first. If you do have to go all the way to court it will be up to the seller to prove that they suffered liquidated damages sufficient to keep your deposit. Basically it will be that the time you kept them off the market inhibited the possible sale. It will be up to a judge to decide. I forgot the small claims limit but I think at 5k you are close to it.
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If you like you can try to renegotiate the purchase price. However if you are thinking that 10-15k on the deal will insulate you sufficiently from further depreciation then I believe you are mistaken. I take it this is an income property investment. Let me ask you this, do you have other rental properties here in town? I think that if you are really going to purchase income properties here in San Diego County you need to very much consider waiting. The risk/reward on you waiting versus buying really plays to a wait decision. The only variable that weighs against your decision are mortgage rates. The thing that concerns me the most is your statement that 10-15k would make you reconsider. If that small of an amount would sway the choice between buying and not buying then something seems odd to me.