A decent 802.11b Wi-Fi access point can be had for between $50 and $100 (in fact, probably for even less than $50). By contrast, an elegant 802.11g unit, the Apple Extreme Base Station, costs about $250 (a little less if you take the model without the external antenna port). Although industrial-strength commercial units can cost a good bit more, the point is that these are not hugely expensive pieces of equipment.
You'll pay more for 802.11g equipment than for 802.11b equipment because 802.11g is newer and faster. This is a choice with obvious trade-offs that you'll have to make.
Likewise, the Apple Extreme Base Station costs a little more than equipment manufactured by a vendor that is not Apple but then again it is a wonderfully designed piece of equipment with extended range, an elegant form factor, and great ease of use.
Even if you buy your access point in the real world of bricks and mortar, it makes sense to at least comparison-shop online. For online shopping tips and tricks, see the sidebar "Comparison Shopping Online" in Chapter 8, "Adding Wi-Fi to a Mobile Computer."
I'm a firm believer in buying equipment from quality vendors that stand behind their products. Quality manufacturers of Wi-Fi access points include
Linksys (owned by Cisco)