The idea of your self concept being a huge part of your purchase decision is absolutely true without a doubt. Self concept is basically how we see ourselves and how we think other people see us, and as individuals we often try to create a picture of ourselves that is acceptable to our reference groups and makes us feel better about ourselves.
The psychology of buying is simple. When it comes to buying of cars, take for instance you choose to buy a Mercedes Benz car. You may convince yourself that the purchase is just because you love the car or because it has great engine power but in the reality of things it is because of how you believe you would feel when you actually own the car; the sense of power, pride, luxury and envy from others. Another instance may be when you want to buy a clothing item or clothing accessory, you buy them because you believe they make you look attractive, beautiful, expensive, classy, fashionable,etc as the case may be.
These instances may not neccesarily apply to you in its actual sense, but the general idea behind it is that when you make a purchase you more often than not attribute it to yourself and how it makes you feel and this action is done consciously or unconsciousy.
It is important that marketers create some form of desire that their potential customers can relate to. Create an avenue that makes your customers feel their purchase is worth it and at the same time makes them feel good about themselves, because no one really wants to make a purchase that makes them feel inferior or not good enough. People want products that make them feel great about themselves so its worth the cost of the purchase.
My ideas may not be perfect but your opinions would always count and ideas duly noted. These are thoughts from ME to YOU.
Have a wonderful day.