Maybe it's a good idea, maybe it's not. Here's my opinion:

A lot of high profile designers or multimedia and development firms don't showcase any of their prices publicly, due to the fact that having the customer inquire about the pricing, leaves them open to initiate a sales pitch and possibly snag potential clients. It also allows the freedom of "specific quotation" if you will. It's a much more personal approach to providing information about a service, which the potential customer is obviously interested in, as they have inquired about prices in the first place.

It's all a sales tactic in my opinion. However I may be wrong