Your agent didn't do his homework and didn't tell you all the risks as previous posters pointed out. As I understand it, short sales are done routinely, but the final blessing needs to come from the seller's mortgagee, and is often dependant on the final negotiated price. There should be (or should have been) such a clause in the agreement. This way, you could've decided for yourself if it's worth pursuing this sale by investing money into inspections and appraisals, and rearranging your life for this purchase. Your realtor really goofed.
At this point, this makes the koi pond issue rather miniscule!
[rant] To go a little off topic, It really frosts me how some realtors can charge 4%, 5%, 6%, or sometimes even 7% to broker a sale. That's often 6% of a person's entire wealth. I know how hard I work for that kind of money. I just don't see realtors working that hard for that kind of money, especially Cutehumor's agent. We're basically paying 6% of our wealth just to get our houses listed into a computer database! [/rant]