Terrell,
A rule of thumb is a 1% binder against the purchase price. However, the seller may ask for more in negotiations. Selling high end homes is really tough these days, so negotiate heavily on the purchase price.
Also, a high end purchase will require "proof of funds"...basically evidence that you would be able to complete the sale. If you can prove you'll be doing a 20% down payment and can get a jumbo loan, then you often won't need a large earnest money deposit. If you can't prove that, then you can expect to pay a higher earnest money deposit.
There is a lot more to it than one simple number, since every purchase is different. - Wed Dec 30 2009, 22:26