Which do you consider first before you select to Sell or Market a Product? Cost , Quality or Usage?

It depends on product to product.  In some cases where your target market is too limited you will put cost on your first priority. While in other case where you are hitting the very high end of the market, along with the cost you have to give priority to the quality. In another case where you think that your product is used by masses, you can certainly have to consider the cost but your main focus will be the maximum number of uses or usages.

i must say cost, because first we must see the volume sales, once the product reach to the maximum number of users then they can give you the feedback by constantly buying the products or not . Once we hit our expected target sales numbers then we can decide about the pricing like increase in price or decrease in price.  So for every new launch product we must hit the volume sales....

I check the quality fest of all