Don't apologize when you increase your prices. Businesses increase prices for two main reasons - either their costs have increased so they need to increase prices to maintain margins, or the business believes that the current prices do not adequately reflect the value of the goods or services they are now providing. So there is no need for the business owner to be defensive and to apologize.
I have often seen letters from suppliers that begin with an apology. "I am sorry to inform you that due to increased costs, we find it necessary to increase our prices." Why do they feel it is necessary to apologize for wanting to make a reasonable profit? Why apologize when you want your price to reflect the value of what you supply?
First of all, no one really cares about anyone else's costs. When you buy a car, do you really care about how much the dealer is paying in property tax? If you are getting a new roof for your house, do you really care about the workers compensation premium paid by the roofing company? Of course not. You are concerned about getting the most value for your dollar. Most people choose products based on whether or not it brings them the value (or pleasure) that they want. Just because a person can afford a $50,000 car does not mean they will buy a $50,000 car. The $25,000 extra that they can afford to pay for buying one car instead of another, may not bring them $25,000 more value (or pleasure or satisfaction - whatever term you choose to use). Thus, no one is willing to pay more just because the seller's costs have increased. So why even talk about your costs.
My advice to clients is to notify clients in a positive manner not a negative manner. Let clients know that you offer a product that is certainly worth what you are charging. Tell them that based on the value (quality, special service, warranty, etc.) that you provide, you are now increasing your prices to reflect that value. That's it. No further explanation is needed. If they agree, they will continue to buy from you at the higher price. If they do not feel that your product provides a value equal to the price, they will not continue to buy from you - regardless of your increased costs.
Be positive. Be direct. Be bold. You need to make a reasonable profit and you need for your prices to reflect what you offer. That's my opinion. Please feel free to express yours in the comments section.