Gardiner & Theobald provides a very useful cost comparison between wired and wireless networks (14 July, page 80). Wireless technology is shown to be about 35% the cost of a wired network.
However, the wired network example he uses would typically deliver 100 Mbps bandwidth at each desk while the wireless network has 10 users sharing a 54 Mbps wireless access point.
This gives only about 5 Mbps per user, which is 1/20th of the capacity of the wired example. As always you pay your money and take your choice. Wireless networks are ideal where you have lots of space and few, or occasional, users; wired networks still have their place in offices, dealing rooms and calls centres especially where both the VoIP phone and PC share the wired connection.
John Lane, Cundall