It's really dangerous mentioning dollars-and-cents figures in a book for several reasons. The cost of computer-related devices is constantly changing, mostly going down over time as specific technologies become more mainstream. It's a safe bet that it will cost less to create a Wi-Fi network by the time you read this book than it cost as I was writing it.
It is also true that there are many different possible network configurations, as I've explained earlier in this chapter. Your network is unlikely to be my network. The cost of setting up your Wi-Fi network will largely depend on how many devices you need to equip with Wi-Fi.
That said, although it's still more expensive than setting up a small wired network, the bottom line is that it is relatively cheap to set up a Wi-Fi network, or add Wi-Fi to your existing network.
Here's the ballpark as of today:
You can get good wireless Wi-Fi cards for laptops for less than $60 U.S. each.
Adding Wi-Fi to a desktop computer should cost even less than adding it to a laptop.
Buying a new device with Wi-Fi capabilities should add very little to the incremental cost of the device (perhaps $20?$30).
There's a great variety in the cost of access points, starting at below $100 and going up to more than $1,000. The primary distinction is the range of Wi-Fi broadcasts. Most likely you can get a perfectly reasonable Wi-Fi access point for a good bit less than $100. By way of comparison, the incredibly nifty and easy-to-install Apple Airport Extreme (802.11g) sells for about $250.
You can get a good Wi-Fi router for slightly less than $100.
The Absolute Minimum
Here are the key points to remember from this chapter: