Prudential Real Estate of the Rockies
Unfortunately if you sign a waiver and don't have other avenues to get out of a contract (i.e., unsatisfactory conditions discovered in an inspection - if this is a condition in your contract), you will have to forfeit your earnest money if you later change your mind and decide to not purchase a property.
If you love the house, find some more negotiating points to discuss. These days appraisals are important.
If you waive the appraisal contingency, then you will not be able to terminate the contract for appraisal conditions. If you are getting a loan on the property the bank will HAVE to appraise it for the contract price.
Check with your agent about the details on your contract.
Keller Williams Realty Success
You could lose your earnest money if you back out of your contract outside of all contingencies / deadlines. Again, please consult with your mortgage broker before signing any appraisal waiver.