Is Selling to an existing customer more COST EFFECTIVE than to a new customer?

Sometimes exisiting customer can be more demanding than new one. But incase of new one you might have to spend more time inorder to convince him.

There is a Cost involved i finding and accuring a new customer 

This is a necessary evil 

To an Exsisting customer you are a known devil hence would prefer to do business with you with in reasonable limits 

Definitely, as with an existing customer, you have already established a strong relationship to do business and they know what to expect from you.  In addition, if you are running out of time to meet your monthly target, such customers are always valuable.   There is no need to waste time, money or energy to convince them to buy your products, so it saves on all these factors and requires less efforts to business.

Whereas, for a new customer, you have to spend time, money and energy to create a relationship, cannot expect them to be loyal, as they may be testing you out and they are of no help in times when you have to meet your monthly target. 

The only benefit here when looking out for new customers is that they give you the opportunity to explore new market zones, something which an existing customer cannot or will not do for you.

Yes, it's more cost effective because you have already invested time and money to establish that relationship. Some of the costs that you may save with existing customers are; doing a background check on new customer, cost of account and profile setup, cost of educating the customer, cost of obtain the necessary documents, cost of mailing out the necessary documents, cost of conducting conference calls and meetings to select the right product and the possibility of the customer returning the product or canceling the service due to not meeting expectations.

Yes because you save on marketing and cold calling cost

All the surveys and research claim its five times cheaper ... and personally i believe it to 

I don't think the way of selling change between an existing customer and a new customer cause effective exists in both cases. The difference is between an impulsive customer who may buy anything you proceed& the new customer who is experimented his new experience with you as a seller. The technique of sale are the same in both cases.

Yes.it cost  3 times more to acquire a customer than to retain a customer.

With regard to new customers, operating costs are presumed to rise as the customer has to learn the 

procedures of the firm, and the firm has to learn the needs of its new customer.

What I think is as mentioned below:

Sales to existing customer is already a ongoing continous process so how could we define it as cost effective sales ? This sale we can assume as continuity to business for what we have already invested in that customer, but we can try to increase the level of sales as normally no extra cost or efforts are required to maintain a existing customer unless any dispute arises.

Sales to new tied customers and benefiting the corporation with targeted revenue generation is better but going ahead of assumptions in the means of Profitablity to new customer and organization may be described as COST EFFECTIVE SALES.

This is what I have experienced, please let me know your views also,

thnx to all

To develop Brand loyalty to the existing customers and attracting to the new customers even in new markets both are the cost effective measures.