I am selling a product which has a special addition to it which is not available elsewhere; for that a customer is willing to pay extra money. However, what he does not know is that special feature will be available everywhere in a week. Thus he need not pay the extra money if he waits a week and can buy it anywhere. Telling him that would lose me the extra money and perhaps the customer itself. If I don't give him that information (he hasn't asked about it) will it be equivalent to lying? Am I walking a grey area?
Yeah, you are somewhere in the grey area.
Let me support it with a story. A and B fall for the same girl. A takes the girl. After a while B goes to his friend and says "I saw a man kissing this girl". A gets jealous and leaves the girl. B gets her.
After a while A asks B "who was the man". B says "Her father".
B has not lied, it as A's job to be more careful.
If I make an analogy to your case, I can not say that there is a sin in what you do. The customer has not asked, it is his responsibility to be careful. Although, there might be no sin in what you do. I believe there might be reward if you tell the truth to the customer.