That's an issue I deal with daily. In my case, people arrive expecting to pay $10 or $100 for a domain name; and I'm obliged to educate them by referencing related sales anywhere from $1,000 to $10,000,000.

We're all reluctant to spend larger amounts without a reference point. In the case of service costs, we can usually compare competitors' rates. Fortunately, you have no competitors! Therefore, you'll want to emphasize what you DO have:

Happy customers.

You'll quickly establish yourself. Suppose I'm next in line but reluctant to pay. Showcase reviews! Show pictures! Emphasize that the real-world market wants what you offer and pays your fair price. Accentuate the fact that people like me DO hire you, which validates your price structure.

Nobody wants to be the guinea pig or look foolish all by himself / herself. There's safety in numbers.