Once all the matters, financial/otherwise are settled between the parties, it is better to give an advance and write an agreement. This ensures that the owner does not change his word regarding the cost as well as make a sale to someone else who offers more money. The agreement should be written in 50 Rs stamp paper. The agreement should state the actual cost, the advance amount, the time span within which the actual sale should take place and how to proceed in case of any default from either parties, to cover the loss. The agreement can be prepared by a experts and should be signed by both the parties and two witnesses. After signing the agreement if one of the parties makes a default, the other party can take legal action against him.