Think of it like this - you're out window shopping, and you look in the window of a gorgeous shop with beautiful things you'd love to buy. You can see that there are price labels but they are all turned upside down so that you can't see them, hidden from view. What do you tend to think? My reaction is one of two things - I can't afford the items I am looking at (or the shop wants me to think I can't afford them), or the shop is using this as a way to get me into their store and then start their hard sell on me. Either way, I'm likely to walk on and spend my disposable income elsewhere - even when I can afford the items in the store.
If competitors want to know our prices, they have all kinds of tactics they can employ to find out what they are - the simplest being to ring up and pretend they are a prospective client of ours and ask us what our prices are. Don't lose prospective clients through fear of others finding out what you charge. Be honest, be upfront, tell your clients your prices and if it's right to do so, advertise them on your website.
And if you are the competitor off on the hunt for others' prices, remember, their price is only half of the story. To truly understand their pricing strategy you also need to know what their costs are, what business model they are operating to, what value they attach to their product or service, and so on. Knowing their prices alone actually tells you very little beyond a number.
You want to attract customers? Get over the fear, and develop the courage to spill the beans on your company secrets.