There are a couple of factors at work. One is simply "too much knowledge."
The clerk at the supermarket has no idea what that loaf of bread costs the store. All she does is charge the price the register tells her to charge.
You, on the other hand, had to make up the price yourself. Unlike the clerk, you have some idea as to how much "wiggle room" there is. What you lack is the confidence, the certainty, to know your price is right and just.
There is also the element of "not enough information."
That same customer is free to peruse the bread aisle, and make his selection. He can decide whether to get the 50 cent generic loaf, or the $5 designer loaf. He knows he's in charge.
When he's speaking to you, he lacks this information. He worries, because he has to rely on your making decisions for him.
A primary rule of business is to NOT let your product become a 'commodity.' If the customer sees another price, he needs to already know why yours is different.
You must sell on service and quality- and not on price. Then let your price stand on its' own. Let the customer decide: does he want a "Wal Mart" cheap, crowded store, low quality experience.... or does he want the upscale, relaxing, reliable "Macy's" treatment?
If he defers, now is your time to be gracious. Let him know that his request is perfectly reasonable, and someday he will be in a position to use your services. Let him have his dignity.
There's even a good chance that he will decide to find a way to afford you- after someone else gives him the 'brush off.' Or, treats HIM like he's a commodity.